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The Book
Version: 3.0
generated on April 28, 2016

The Book (3.0)
This work is licensed under the “Attribution-Share Alike 3.0 Unported” license (http://creativecommons.org/
licenses/by-sa/3.0/).
You are free to share (to copy, distribute and transmit the work), and to remix (to adapt the work) under the
following conditions:
• Attribution: You must attribute the work in the manner specified by the author or licensor (but
not in any way that suggests that they endorse you or your use of the work).
• Share Alike: If you alter, transform, or build upon this work, you may distribute the resulting work
only under the same, similar or a compatible license. For any reuse or distribution, you must make
clear to others the license terms of this work.
The information in this book is distributed on an “as is” basis, without warranty. Although every precaution
has been taken in the preparation of this work, neither the author(s) nor SensioLabs shall have any liability to
any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by
the information contained in this work.
If you find typos or errors, feel free to report them by creating a ticket on the Symfony ticketing system
(http://github.com/symfony/symfony-docs/issues). Based on tickets and users feedback, this book is
continuously updated.

Contents at a Glance
Symfony and HTTP Fundamentals ......................................................................................................4
Symfony versus Flat PHP...................................................................................................................14
Installing and Configuring Symfony...................................................................................................26
Create your First Page in Symfony .....................................................................................................33
Controller.........................................................................................................................................42
Routing ............................................................................................................................................55
Creating and Using Templates...........................................................................................................71
Configuring Symfony (and Environments) .........................................................................................90
The Bundle System ...........................................................................................................................94
Databases and Doctrine ....................................................................................................................98
Databases and Propel ...................................................................................................................... 119
Testing ........................................................................................................................................... 120
Validation....................................................................................................................................... 136
Forms ............................................................................................................................................. 149
Security .......................................................................................................................................... 175
HTTP Cache................................................................................................................................... 189
Translations.................................................................................................................................... 206
Service Container ............................................................................................................................ 218
Performance ................................................................................................................................... 231

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Contents at a Glance | iii

Chapter 1

Symfony and HTTP Fundamentals
Congratulations! By learning about Symfony, you're well on your way towards being a more productive,
well-rounded and popular web developer (actually, you're on your own for the last part). Symfony is built
to get back to basics: to develop tools that let you develop faster and build more robust applications,
while staying out of your way. Symfony is built on the best ideas from many technologies: the tools and
concepts you're about to learn represent the efforts of thousands of people, over many years. In other
words, you're not just learning "Symfony", you're learning the fundamentals of the web, development
best practices and how to use many amazing new PHP libraries, inside or independently of Symfony. So,
get ready.
True to the Symfony philosophy, this chapter begins by explaining the fundamental concept common
to web development: HTTP. Regardless of your background or preferred programming language, this
chapter is a must-read for everyone.

HTTP is Simple
HTTP (Hypertext Transfer Protocol to the geeks) is a text language that allows two machines to
communicate with each other. That's it! For example, when checking for the latest xkcd1 comic, the
following (approximate) conversation takes place:

1. http://xkcd.com/

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Chapter 1: Symfony and HTTP Fundamentals | 4

And while the actual language used is a bit more formal, it's still dead-simple. HTTP is the term used to
describe this simple text-based language. No matter how you develop on the web, the goal of your server
is always to understand simple text requests, and return simple text responses.
Symfony is built from the ground up around that reality. Whether you realize it or not, HTTP is
something you use every day. With Symfony, you'll learn how to master it.

Step1: The Client Sends a Request
Every conversation on the web starts with a request. The request is a text message created by a client (e.g.
a browser, a smartphone app, etc) in a special format known as HTTP. The client sends that request to a
server, and then waits for the response.
Take a look at the first part of the interaction (the request) between a browser and the xkcd web server:

In HTTP-speak, this HTTP request would actually look something like this:
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GET / HTTP/1.1
Host: xkcd.com
Accept: text/html
User-Agent: Mozilla/5.0 (Macintosh)

This simple message communicates everything necessary about exactly which resource the client is
requesting. The first line of an HTTP request is the most important and contains two things: the URI and
the HTTP method.
The URI (e.g. /, /contact, etc) is the unique address or location that identifies the resource the client
wants. The HTTP method (e.g. GET) defines what you want to do with the resource. The HTTP methods
are the verbs of the request and define the few common ways that you can act upon the resource:
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Chapter 1: Symfony and HTTP Fundamentals | 5

GET

Retrieve the resource from the server

POST

Create a resource on the server

PUT

Update the resource on the server

DELETE Delete the resource from the server
With this in mind, you can imagine what an HTTP request might look like to delete a specific blog entry,
for example:
Listing 1-2

1 DELETE /blog/15 HTTP/1.1

There are actually nine HTTP methods (also known as verbs) defined by the HTTP specification,
but many of them are not widely used or supported. In reality, many modern browsers only
support POST and GET in HTML forms. Various others are however supported in
XMLHttpRequests, as well as by Symfony's router.

In addition to the first line, an HTTP request invariably contains other lines of information called request
headers. The headers can supply a wide range of information such as the requested Host, the response
formats the client accepts (Accept) and the application the client is using to make the request (UserAgent). Many other headers exist and can be found on Wikipedia's List of HTTP header fields2 article.

Step 2: The Server Returns a Response
Once a server has received the request, it knows exactly which resource the client needs (via the URI)
and what the client wants to do with that resource (via the method). For example, in the case of a GET
request, the server prepares the resource and returns it in an HTTP response. Consider the response from
the xkcd web server:

Translated into HTTP, the response sent back to the browser will look something like this:
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HTTP/1.1 200 OK
Date: Sat, 02 Apr 2011 21:05:05 GMT
Server: lighttpd/1.4.19
Content-Type: text/html


2. https://en.wikipedia.org/wiki/List_of_HTTP_header_fields

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Chapter 1: Symfony and HTTP Fundamentals | 6

7

8

The HTTP response contains the requested resource (the HTML content in this case), as well as other
information about the response. The first line is especially important and contains the HTTP response
status code (200 in this case). The status code communicates the overall outcome of the request back
to the client. Was the request successful? Was there an error? Different status codes exist that indicate
success, an error, or that the client needs to do something (e.g. redirect to another page). A full list can
be found on Wikipedia's List of HTTP status codes3 article.
Like the request, an HTTP response contains additional pieces of information known as HTTP headers.
For example, one important HTTP response header is Content-Type. The body of the same resource
could be returned in multiple different formats like HTML, XML, or JSON and the Content-Type header
uses Internet Media Types like text/html to tell the client which format is being returned. You can see a
list of common media types4 from IANA.
Many other headers exist, some of which are very powerful. For example, certain headers can be used to
create a powerful caching system.

Requests, Responses and Web Development
This request-response conversation is the fundamental process that drives all communication on the web.
And as important and powerful as this process is, it's inescapably simple.
The most important fact is this: regardless of the language you use, the type of application you build
(web, mobile, JSON API) or the development philosophy you follow, the end goal of an application is
always to understand each request and create and return the appropriate response.
Symfony is architected to match this reality.
To learn more about the HTTP specification, read the original HTTP 1.1 RFC5 or the HTTP Bis6,
which is an active effort to clarify the original specification. A great tool to check both the request
and response headers while browsing is the Live HTTP Headers7 extension for Firefox.

Requests and Responses in PHP
So how do you interact with the "request" and create a "response" when using PHP? In reality, PHP
abstracts you a bit from the whole process:
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$uri = $_SERVER['REQUEST_URI'];
$foo = $_GET['foo'];
header('Content-Type: text/html');
echo 'The URI requested is: '.$uri;
echo 'The value of the "foo" parameter is: '.$foo;

As strange as it sounds, this small application is in fact taking information from the HTTP request and
using it to create an HTTP response. Instead of parsing the raw HTTP request message, PHP prepares
superglobal variables such as $_SERVER and $_GET that contain all the information from the request.
3. https://en.wikipedia.org/wiki/List_of_HTTP_status_codes
4.
5.
6.
7.

https://www.iana.org/assignments/media-types/media-types.xhtml
http://www.w3.org/Protocols/rfc2616/rfc2616.html
http://datatracker.ietf.org/wg/httpbis/
https://addons.mozilla.org/en-US/firefox/addon/live-http-headers/

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Chapter 1: Symfony and HTTP Fundamentals | 7

Similarly, instead of returning the HTTP-formatted text response, you can use the header() function to
create response headers and simply print out the actual content that will be the content portion of the
response message. PHP will create a true HTTP response and return it to the client:
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HTTP/1.1 200 OK
Date: Sat, 03 Apr 2011 02:14:33 GMT
Server: Apache/2.2.17 (Unix)
Content-Type: text/html
The URI requested is: /testing?foo=symfony
The value of the "foo" parameter is: symfony

Requests and Responses in Symfony
Symfony provides an alternative to the raw PHP approach via two classes that allow you to interact
with the HTTP request and response in an easier way. The Request8 class is a simple object-oriented
representation of the HTTP request message. With it, you have all the request information at your
fingertips:
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use Symfony\Component\HttpFoundation\Request;
$request = Request::createFromGlobals();

// the URI being requested (e.g. /about) minus any query parameters
$request->getPathInfo();
// retrieve GET and POST variables respectively
$request->query->get('foo');
$request->request->get('bar', 'default value if bar does not exist');
// retrieve SERVER variables
$request->server->get('HTTP_HOST');
// retrieves an instance of UploadedFile identified by foo
$request->files->get('foo');
// retrieve a COOKIE value
$request->cookies->get('PHPSESSID');
// retrieve an HTTP request header, with normalized, lowercase keys
$request->headers->get('host');
$request->headers->get('content_type');
$request->getMethod();
// GET, POST, PUT, DELETE, HEAD
$request->getLanguages(); // an array of languages the client accepts

As a bonus, the Request class does a lot of work in the background that you'll never need to worry about.
For example, the isSecure() method checks the three different values in PHP that can indicate whether
or not the user is connecting via a secured connection (i.e. HTTPS).

8. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Request.html

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Chapter 1: Symfony and HTTP Fundamentals | 8

ParameterBags and Request Attributes
As seen above, the $_GET and $_POST variables are accessible via the public query and request
properties respectively. Each of these objects is a ParameterBag9 object, which has methods like
get()10, has()11, all()12 and more. In fact, every public property used in the previous example is
some instance of the ParameterBag.
The Request class also has a public attributes property, which holds special data related to how
the application works internally. For the Symfony Framework, the attributes holds the values
returned by the matched route, like _controller, id (if you have an {id} wildcard), and even the
name of the matched route (_route). The attributes property exists entirely to be a place where
you can prepare and store context-specific information about the request.

Symfony also provides a Response class: a simple PHP representation of an HTTP response message.
This allows your application to use an object-oriented interface to construct the response that needs to
be returned to the client:
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use Symfony\Component\HttpFoundation\Response;
$response = new Response();
$response->setContent('

Hello world!

');
$response->setStatusCode(Response::HTTP_OK);
$response->headers->set('Content-Type', 'text/html');

// prints the HTTP headers followed by the content
$response->send();

If Symfony offered nothing else, you would already have a toolkit for easily accessing request information
and an object-oriented interface for creating the response. Even as you learn the many powerful features
in Symfony, keep in mind that the goal of your application is always to interpret a request and create the
appropriate response based on your application logic.
The Request and Response classes are part of a standalone component included with Symfony
called HttpFoundation. This component can be used entirely independently of Symfony and also
provides classes for handling sessions and file uploads.

The Journey from the Request to the Response
Like HTTP itself, the Request and Response objects are pretty simple. The hard part of building an
application is writing what comes in between. In other words, the real work comes in writing the code
that interprets the request information and creates the response.
Your application probably does many things, like sending emails, handling form submissions, saving
things to a database, rendering HTML pages and protecting content with security. How can you manage
all of this and still keep your code organized and maintainable?
Symfony was created to solve these problems so that you don't have to.

9.
10.
11.
12.

http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/ParameterBag.html
http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/ParameterBag.html#method_get
http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/ParameterBag.html#method_has
http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/ParameterBag.html#method_all

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Chapter 1: Symfony and HTTP Fundamentals | 9

The Front Controller
Traditionally, applications were built so that each "page" of a site was its own physical file:
Listing 1-8

1 index.php
2 contact.php
3 blog.php

There are several problems with this approach, including the inflexibility of the URLs (what if you
wanted to change blog.php to news.php without breaking all of your links?) and the fact that each file
must manually include some set of core files so that security, database connections and the "look" of the
site can remain consistent.
A much better solution is to use a front controller: a single PHP file that handles every request coming
into your application. For example:
/index.php

executes index.php

/index.php/contact executes index.php
/index.php/blog

executes index.php

Using Apache's mod_rewrite (or equivalent with other web servers), the URLs can easily be
cleaned up to be just /, /contact and /blog.

Now, every request is handled exactly the same way. Instead of individual URLs executing different PHP
files, the front controller is always executed, and the routing of different URLs to different parts of your
application is done internally. This solves both problems with the original approach. Almost all modern
web apps do this - including apps like WordPress.

Stay Organized
Inside your front controller, you have to figure out which code should be executed and what the content
to return should be. To figure this out, you'll need to check the incoming URI and execute different parts
of your code depending on that value. This can get ugly quickly:
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// index.php
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
$request = Request::createFromGlobals();
$path = $request->getPathInfo(); // the URI path being requested
if (in_array($path, array('', '/'))) {
$response = new Response('Welcome to the homepage.');
} elseif ('/contact' === $path) {
$response = new Response('Contact us');
} else {
$response = new Response('Page not found.', Response::HTTP_NOT_FOUND);
}
$response->send();

Solving this problem can be difficult. Fortunately it's exactly what Symfony is designed to do.

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Chapter 1: Symfony and HTTP Fundamentals | 10

The Symfony Application Flow
When you let Symfony handle each request, life is much easier. Symfony follows the same simple pattern
for every request:

Incoming requests are interpreted by the routing and passed to controller functions that return Response
objects.
Each "page" of your site is defined in a routing configuration file that maps different URLs to different
PHP functions. The job of each PHP function, called a controller, is to use information from the request
- along with many other tools Symfony makes available - to create and return a Response object. In other
words, the controller is where your code goes: it's where you interpret the request and create a response.
It's that easy! To review:
• Each request executes a front controller file;
• The routing system determines which PHP function should be executed based on information
from the request and routing configuration you've created;
• The correct PHP function is executed, where your code creates and returns the appropriate
Response object.

A Symfony Request in Action
Without diving into too much detail, here is this process in action. Suppose you want to add a /contact
page to your Symfony application. First, start by adding an entry for /contact to your routing
configuration file:
Listing 1-10

1 # app/config/routing.yml
2 contact:
3
path:
/contact
4
defaults: { _controller: AppBundle:Main:contact }

When someone visits the /contact page, this route is matched, and the specified controller is executed.
As you'll learn in the routing chapter, the AppBundle:Main:contact string is a short syntax that points to
a specific PHP method contactAction inside a class called MainController:
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// src/AppBundle/Controller/MainController.php
namespace AppBundle\Controller;
use Symfony\Component\HttpFoundation\Response;
class MainController
{

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Chapter 1: Symfony and HTTP Fundamentals | 11

8
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12 }

public function contactAction()
{
return new Response('

Contact us!

');
}

In this very simple example, the controller simply creates a Response13 object with the HTML

Contact us!

. In the controller chapter, you'll learn how a controller can render templates,
allowing your "presentation" code (i.e. anything that actually writes out HTML) to live in a separate
template file. This frees up the controller to worry only about the hard stuff: interacting with the
database, handling submitted data, or sending email messages.

Symfony: Build your App, not your Tools
You now know that the goal of any app is to interpret each incoming request and create an appropriate
response. As an application grows, it becomes more difficult to keep your code organized and
maintainable. Invariably, the same complex tasks keep coming up over and over again: persisting things
to the database, rendering and reusing templates, handling form submissions, sending emails, validating
user input and handling security.
The good news is that none of these problems is unique. Symfony provides a framework full of tools that
allow you to build your application, not your tools. With Symfony, nothing is imposed on you: you're
free to use the full Symfony Framework, or just one piece of Symfony all by itself.

Standalone Tools: The Symfony Components
So what is Symfony? First, Symfony is a collection of over twenty independent libraries that can be used
inside any PHP project. These libraries, called the Symfony Components, contain something useful for
almost any situation, regardless of how your project is developed. To name a few:
HttpFoundation
Contains the Request and Response classes, as well as other classes for handling sessions and file
uploads.
Routing
Powerful and fast routing system that allows you to map a specific URI (e.g. /contact) to some
information about how that request should be handled (e.g. execute the contactAction()
method).
Form
A full-featured and flexible framework for creating forms and handling form submissions.
Validator14
A system for creating rules about data and then validating whether or not user-submitted data
follows those rules.
Templating
A toolkit for rendering templates, handling template inheritance (i.e. a template is decorated with a
layout) and performing other common template tasks.
Security
A powerful library for handling all types of security inside an application.
13. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Response.html
14. https://github.com/symfony/validator

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Chapter 1: Symfony and HTTP Fundamentals | 12

Translation
A framework for translating strings in your application.
Each one of these components is decoupled and can be used in any PHP project, regardless of whether
or not you use the Symfony Framework. Every part is made to be used if needed and replaced when
necessary.

The Full Solution: The Symfony Framework
So then, what is the Symfony Framework? The Symfony Framework is a PHP library that accomplishes
two distinct tasks:
1. Provides a selection of components (i.e. the Symfony Components) and third-party libraries
(e.g. Swift Mailer15 for sending emails);
2. Provides sensible configuration and a "glue" library that ties all of these pieces together.
The goal of the framework is to integrate many independent tools in order to provide a consistent
experience for the developer. Even the framework itself is a Symfony bundle (i.e. a plugin) that can be
configured or replaced entirely.
Symfony provides a powerful set of tools for rapidly developing web applications without imposing on
your application. Normal users can quickly start development by using a Symfony distribution, which
provides a project skeleton with sensible defaults. For more advanced users, the sky is the limit.

15. http://swiftmailer.org/

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Chapter 1: Symfony and HTTP Fundamentals | 13

Chapter 2

Symfony versus Flat PHP
Why is Symfony better than just opening up a file and writing flat PHP?
If you've never used a PHP framework, aren't familiar with the MVC philosophy, or just wonder what
all the hype is around Symfony, this chapter is for you. Instead of telling you that Symfony allows you to
develop faster and better software than with flat PHP, you'll see for yourself.
In this chapter, you'll write a simple application in flat PHP, and then refactor it to be more organized.
You'll travel through time, seeing the decisions behind why web development has evolved over the past
several years to where it is now.
By the end, you'll see how Symfony can rescue you from mundane tasks and let you take back control of
your code.

A Simple Blog in Flat PHP
In this chapter, you'll build the token blog application using only flat PHP. To begin, create a single page
that displays blog entries that have been persisted to the database. Writing in flat PHP is quick and dirty:
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// index.php
$link = new PDO("mysql:host=localhost;dbname=blog_db", 'myuser', 'mypassword');
$result = $link->query('SELECT id, title FROM post');
?>



List of Posts


List of Posts



    fetch(PDO::FETCH_ASSOC)): ?>


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$link = null;
?>

That's quick to write, fast to execute, and, as your app grows, impossible to maintain. There are several
problems that need to be addressed:
• No error-checking: What if the connection to the database fails?
• Poor organization: If the application grows, this single file will become increasingly
unmaintainable. Where should you put code to handle a form submission? How can you
validate data? Where should code go for sending emails?
• Difficult to reuse code: Since everything is in one file, there's no way to reuse any part of the
application for other "pages" of the blog.
Another problem not mentioned here is the fact that the database is tied to MySQL. Though not
covered here, Symfony fully integrates Doctrine1, a library dedicated to database abstraction and
mapping.

Isolating the Presentation
The code can immediately gain from separating the application "logic" from the code that prepares the
HTML "presentation":
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// index.php
$link = new PDO("mysql:host=localhost;dbname=blog_db", 'myuser', 'mypassword');
$result = $link->query('SELECT id, title FROM post');
$posts = array();
while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
$posts[] = $row;
}
$link = null;

// include the HTML presentation code
require 'templates/list.php';

The HTML code is now stored in a separate file (templates/list.php), which is primarily an HTML file
that uses a template-like PHP syntax:
Listing 2-3

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1. http://www.doctrine-project.org

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Chapter 2: Symfony versus Flat PHP | 15

3

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List of Posts
5

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List of Posts


8

17

18

By convention, the file that contains all the application logic - index.php - is known as a "controller".
The term controller is a word you'll hear a lot, regardless of the language or framework you use. It refers
simply to the area of your code that processes user input and prepares the response.
In this case, the controller prepares data from the database and then includes a template to present that
data. With the controller isolated, you could easily change just the template file if you needed to render
the blog entries in some other format (e.g. list.json.php for JSON format).

Isolating the Application (Domain) Logic
So far the application contains only one page. But what if a second page needed to use the same database
connection, or even the same array of blog posts? Refactor the code so that the core behavior and dataaccess functions of the application are isolated in a new file called model.php:
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// model.php
function open_database_connection()
{
$link = new PDO("mysql:host=localhost;dbname=blog_db", 'myuser', 'mypassword');
return $link;
}
function close_database_connection($link)
{
$link = null;
}
function get_all_posts()
{
$link = open_database_connection();
$result = $link->query('SELECT id, title FROM post');
$posts = array();
while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
$posts[] = $row;
}
close_database_connection($link);

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Chapter 2: Symfony versus Flat PHP | 16

26
27 }

return $posts;

The filename model.php is used because the logic and data access of an application is traditionally
known as the "model" layer. In a well-organized application, the majority of the code representing
your "business logic" should live in the model (as opposed to living in a controller). And unlike in
this example, only a portion (or none) of the model is actually concerned with accessing a database.

The controller (index.php) is now very simple:
Listing 2-5

1 require_once 'model.php';
2
3 $posts = get_all_posts();
4
5 require 'templates/list.php';

Now, the sole task of the controller is to get data from the model layer of the application (the model) and
to call a template to render that data. This is a very simple example of the model-view-controller pattern.

Isolating the Layout
At this point, the application has been refactored into three distinct pieces offering various advantages
and the opportunity to reuse almost everything on different pages.
The only part of the code that can't be reused is the page layout. Fix that by creating a new layout.php
file:
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<?php echo $title ?>






The template (templates/list.php) can now be simplified to "extend" the layout:
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4

List of Posts


5

14

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Chapter 2: Symfony versus Flat PHP | 17

15
16

You now have a setup that will allow you to reuse the layout. Unfortunately, to accomplish this, you're
forced to use a few ugly PHP functions (ob_start(), ob_get_clean()) in the template. Symfony uses
a Templating component that allows this to be accomplished cleanly and easily. You'll see it in action
shortly.

Adding a Blog "show" Page
The blog "list" page has now been refactored so that the code is better-organized and reusable. To prove
it, add a blog "show" page, which displays an individual blog post identified by an id query parameter.
To begin, create a new function in the model.php file that retrieves an individual blog result based on a
given id:
Listing 2-8

1
2
3
4
5
6
7
8
9
10
11
12

// model.php
function get_post_by_id($id)
{
$link = open_database_connection();
$id = intval($id);
$result = $link->query('SELECT created_at, title, body FROM post WHERE id = '.$id);
$row = $result->fetch(PDO::FETCH_ASSOC);
close_database_connection($link);
return $row;
}

Next, create a new file called show.php - the controller for this new page:
Listing 2-9

1 require_once 'model.php';
2
3 $post = get_post_by_id($_GET['id']);
4
5 require 'templates/show.php';

Finally, create the new template file - templates/show.php - to render the individual blog post:
Listing 2-10

1
2
3
4
5
6
7
8
9
10
11
12











Creating the second page is now very easy and no code is duplicated. Still, this page introduces even
more lingering problems that a framework can solve for you. For example, a missing or invalid id query
parameter will cause the page to crash. It would be better if this caused a 404 page to be rendered, but
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Chapter 2: Symfony versus Flat PHP | 18

this can't really be done easily yet. Worse, had you forgotten to clean the id parameter via the intval()
function, your entire database would be at risk for an SQL injection attack.
Another major problem is that each individual controller file must include the model.php file. What if
each controller file suddenly needed to include an additional file or perform some other global task (e.g.
enforce security)? As it stands now, that code would need to be added to every controller file. If you forget
to include something in one file, hopefully it doesn't relate to security...

A "Front Controller" to the Rescue
The solution is to use a front controller: a single PHP file through which all requests are processed. With
a front controller, the URIs for the application change slightly, but start to become more flexible:
Listing 2-11

1
2
3
4
5
6
7

Without a front controller
/index.php
=> Blog post list page (index.php executed)
/show.php
=> Blog post show page (show.php executed)
With index.php as the front controller
/index.php
=> Blog post list page (index.php executed)
/index.php/show
=> Blog post show page (index.php executed)

The index.php portion of the URI can be removed if using Apache rewrite rules (or equivalent). In
that case, the resulting URI of the blog show page would be simply /show.

When using a front controller, a single PHP file (index.php in this case) renders every request. For
the blog post show page, /index.php/show will actually execute the index.php file, which is now
responsible for routing requests internally based on the full URI. As you'll see, a front controller is a very
powerful tool.

Creating the Front Controller
You're about to take a big step with the application. With one file handling all requests, you can
centralize things such as security handling, configuration loading, and routing. In this application,
index.php must now be smart enough to render the blog post list page or the blog post show page based
on the requested URI:
Listing 2-12

1
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12
13
14
15
16

// index.php
// load and initialize any global libraries
require_once 'model.php';
require_once 'controllers.php';
// route the request internally
$uri = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
if ('/index.php' === $uri) {
list_action();
} elseif ('/index.php/show' === $uri && isset($_GET['id'])) {
show_action($_GET['id']);
} else {
header('Status: 404 Not Found');
echo '

Page Not Found

';
}

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For organization, both controllers (formerly index.php and show.php) are now PHP functions and each
has been moved into a separate file, controllers.php:
Listing 2-13

1
2
3
4
5
6
7
8
9
10
11

function list_action()
{
$posts = get_all_posts();
require 'templates/list.php';
}
function show_action($id)
{
$post = get_post_by_id($id);
require 'templates/show.php';
}

As a front controller, index.php has taken on an entirely new role, one that includes loading the
core libraries and routing the application so that one of the two controllers (the list_action() and
show_action() functions) is called. In reality, the front controller is beginning to look and act a lot like
Symfony's mechanism for handling and routing requests.
Another advantage of a front controller is flexible URLs. Notice that the URL to the blog post show
page could be changed from /show to /read by changing code in only one location. Before, an
entire file needed to be renamed. In Symfony, URLs are even more flexible.

By now, the application has evolved from a single PHP file into a structure that is organized and allows
for code reuse. You should be happier, but far from satisfied. For example, the "routing" system is
fickle, and wouldn't recognize that the list page (/index.php) should be accessible also via / (if Apache
rewrite rules were added). Also, instead of developing the blog, a lot of time is being spent working on
the "architecture" of the code (e.g. routing, calling controllers, templates, etc.). More time will need to
be spent to handle form submissions, input validation, logging and security. Why should you have to
reinvent solutions to all these routine problems?

Add a Touch of Symfony
Symfony to the rescue. Before actually using Symfony, you need to download it. This can be done by
using Composer, which takes care of downloading the correct version and all its dependencies and
provides an autoloader. An autoloader is a tool that makes it possible to start using PHP classes without
explicitly including the file containing the class.
In your root directory, create a composer.json file with the following content:
Listing 2-14

1 {
2
3
4
5
6
7
8 }

"require": {
"symfony/symfony": "3.0.*"
},
"autoload": {
"files": ["model.php","controllers.php"]
}

Next, download Composer2 and then run the following command, which will download Symfony into a
vendor/ directory:
Listing 2-15

2. https://getcomposer.org/download/

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1 $ composer install

Beside downloading your dependencies, Composer generates a vendor/autoload.php file, which takes
care of autoloading for all the files in the Symfony Framework as well as the files mentioned in the
autoload section of your composer.json.
Core to Symfony's philosophy is the idea that an application's main job is to interpret each request and
return a response. To this end, Symfony provides both a Request3 and a Response4 class. These classes
are object-oriented representations of the raw HTTP request being processed and the HTTP response
being returned. Use them to improve the blog:
Listing 2-16

1
2
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20

// index.php
require_once 'vendor/autoload.php';
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
$request = Request::createFromGlobals();
$uri = $request->getPathInfo();
if ('/' === $uri) {
$response = list_action();
} elseif ('/show' === $uri && $request->query->has('id')) {
$response = show_action($request->query->get('id'));
} else {
$html = '

Page Not Found

';
$response = new Response($html, Response::HTTP_NOT_FOUND);
}

// echo the headers and send the response
$response->send();

The controllers are now responsible for returning a Response object. To make this easier, you can add
a new render_template() function, which, incidentally, acts quite a bit like the Symfony templating
engine:
Listing 2-17

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

// controllers.php
use Symfony\Component\HttpFoundation\Response;
function list_action()
{
$posts = get_all_posts();
$html = render_template('templates/list.php', array('posts' => $posts));
return new Response($html);
}
function show_action($id)
{
$post = get_post_by_id($id);
$html = render_template('templates/show.php', array('post' => $post));
return new Response($html);
}

3. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Request.html
4. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Response.html

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19
20
21
22
23
24
25
26
27
28
29

// helper function to render templates
function render_template($path, array $args)
{
extract($args);
ob_start();
require $path;
$html = ob_get_clean();
return $html;
}

By bringing in a small part of Symfony, the application is more flexible and reliable. The Request
provides a dependable way to access information about the HTTP request. Specifically, the
getPathInfo() method returns a cleaned URI (always returning /show and never /index.php/show).
So, even if the user goes to /index.php/show, the application is intelligent enough to route the request
through show_action().
The Response object gives flexibility when constructing the HTTP response, allowing HTTP headers
and content to be added via an object-oriented interface. And while the responses in this application are
simple, this flexibility will pay dividends as your application grows.

The Sample Application in Symfony
The blog has come a long way, but it still contains a lot of code for such a simple application. Along
the way, you've made a simple routing system and a method using ob_start() and ob_get_clean() to
render templates. If, for some reason, you needed to continue building this "framework" from scratch,
you could at least use Symfony's standalone Routing5 and Templating6 components, which already solve
these problems.
Instead of re-solving common problems, you can let Symfony take care of them for you. Here's the same
sample application, now built in Symfony:
Listing 2-18

1
2
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12
13
14
15
16
17
18
19
20
21

// src/AppBundle/Controller/BlogController.php
namespace AppBundle\Controller;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
class BlogController extends Controller
{
public function listAction()
{
$posts = $this->get('doctrine')
->getManager()
->createQuery('SELECT p FROM AppBundle:Post p')
->execute();
return $this->render('Blog/list.html.php', array('posts' => $posts));
}
public function showAction($id)
{
$post = $this->get('doctrine')
->getManager()

5. https://github.com/symfony/routing
6. https://github.com/symfony/templating

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22
23
24
25
26
27
28
29
30
31
32 }

->getRepository('AppBundle:Post')
->find($id);
if (!$post) {
// cause the 404 page not found to be displayed
throw $this->createNotFoundException();
}
return $this->render('Blog/show.html.php', array('post' => $post));
}

The two controllers are still lightweight. Each uses the Doctrine ORM library to retrieve objects from
the database and the Templating component to render a template and return a Response object. The list
template is now quite a bit simpler:
Listing 2-19

1
2
3
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5
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8
9
10
11
12
13
14
15
16
17
18


extend('layout.html.php') ?>
set('title', 'List of Posts') ?>

List of Posts




The layout is nearly identical:
Listing 2-20

1
2
3
4
5
6
7
8
9
10
11
12
13





<?php echo $view['slots']->output(<br /> 'title',<br /> 'Default title'<br /> ) ?>


output('_content') ?>



The show template is left as an exercise, as it should be trivial to create based on the list template.

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Chapter 2: Symfony versus Flat PHP | 23

When Symfony's engine (called the Kernel) boots up, it needs a map so that it knows which controllers
to execute based on the request information. A routing configuration map provides this information in a
readable format:
Listing 2-21

1 # app/config/routing.yml
2 blog_list:
3
path:
/blog
4
defaults: { _controller: AppBundle:Blog:list }
5
6 blog_show:
7
path:
/blog/show/{id}
8
defaults: { _controller: AppBundle:Blog:show }

Now that Symfony is handling all the mundane tasks, the front controller is dead simple. And since it
does so little, you'll never have to touch it once it's created (and if you use a Symfony distribution7, you
won't even need to create it!):
Listing 2-22

1
2
3
4
5
6
7
8

// web/app.php
require_once __DIR__.'/../app/bootstrap.php';
require_once __DIR__.'/../app/AppKernel.php';
use Symfony\Component\HttpFoundation\Request;
$kernel = new AppKernel('prod', false);
$kernel->handle(Request::createFromGlobals())->send();

The front controller's only job is to initialize Symfony's engine (Kernel) and pass it a Request object to
handle. Symfony's core then uses the routing map to determine which controller to call. Just like before,
the controller method is responsible for returning the final Response object. There's really not much else
to it.
For a visual representation of how Symfony handles each request, see the request flow diagram.

Where Symfony Delivers
In the upcoming chapters, you'll learn more about how each piece of Symfony works and the
recommended organization of a project. For now, have a look at how migrating the blog from flat PHP
to Symfony has improved life:
• Your application now has clear and consistently organized code (though Symfony doesn't
force you into this). This promotes reusability and allows for new developers to be productive
in your project more quickly;
• 100% of the code you write is for your application. You don't need to develop or maintain
low-level utilities such as autoloading, routing, or rendering controllers;
• Symfony gives you access to open source tools such as Doctrine and the Templating,
Security, Form, Validation and Translation components (to name a few);
• The application now enjoys fully-flexible URLs thanks to the Routing component;
• Symfony's HTTP-centric architecture gives you access to powerful tools such as HTTP
caching powered by Symfony's internal HTTP cache or more powerful tools such as
Varnish8. This is covered in a later chapter all about caching.
And perhaps best of all, by using Symfony, you now have access to a whole set of high-quality open
source tools developed by the Symfony community! A good selection of Symfony community tools
can be found on KnpBundles.com9.
7. https://github.com/symfony/symfony-standard
8. https://www.varnish-cache.org/

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Better Templates
If you choose to use it, Symfony comes standard with a templating engine called Twig10 that makes
templates faster to write and easier to read. It means that the sample application could contain even less
code! Take, for example, the list template written in Twig:
Listing 2-23

1
2
3
4
5
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7
8
9
10
11
12
13
14
15
16
17

{# app/Resources/views/blog/list.html.twig #}
{% extends "layout.html.twig" %}
{% block title %}List of Posts{% endblock %}
{% block body %}

List of Posts



{% endblock %}

The corresponding layout.html.twig template is also easier to write:
Listing 2-24

1
2
3
4
5
6
7
8
9
10

{# app/Resources/views/layout.html.twig #}



{% block title %}Default title{% endblock %}


{% block body %}{% endblock %}



Twig is well-supported in Symfony. And while PHP templates will always be supported in Symfony, the
many advantages of Twig will continue to be discussed. For more information, see the templating chapter.

Learn more from the Cookbook
• How to Use PHP instead of Twig for Templates
• How to Define Controllers as Services

9. http://knpbundles.com/
10. http://twig.sensiolabs.org

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Chapter 3

Installing and Configuring Symfony
Welcome to Symfony! Starting a new Symfony project is easy. In fact, you'll have your first working
Symfony application up and running in just a few short minutes.
Do you prefer video tutorials? Check out the Joyful Development with Symfony1 screencast series from
KnpUniversity.

To make creating new applications even simpler, Symfony provides an installer. Downloading it is your
first step.

Installing the Symfony Installer
Using the Symfony Installer is the only recommended way to create new Symfony applications. This
installer is a PHP application that has to be installed in your system only once and then it can create any
number of Symfony applications.
The installer requires PHP 5.4 or higher. If you still use the legacy PHP 5.3 version, you cannot
use the Symfony Installer. Read the Creating Symfony Applications without the Installer section to
learn how to proceed.

Depending on your operating system, the installer must be installed in different ways.

Linux and Mac OS X Systems
Open your command console and execute the following commands:
Listing 3-1

1 $ sudo curl -LsS https://symfony.com/installer -o /usr/local/bin/symfony
2 $ sudo chmod a+x /usr/local/bin/symfony

This will create a global symfony command in your system.

1. http://knpuniversity.com/screencast/symfony

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Windows Systems
Open your command console and execute the following command:
Listing 3-2

1 c:\> php -r "readfile('https://symfony.com/installer');" > symfony

Then, move the downloaded symfony file to your project's directory and execute it as follows:
Listing 3-3

1 c:\> move symfony c:\projects
2 c:\projects\> php symfony

Creating the Symfony Application
Once the Symfony Installer is available, create your first Symfony application with the new command:
Listing 3-4

# Linux, Mac OS X
$ symfony new my_project_name

1
2
3
4
5
6

# Windows
c:\> cd projects/
c:\projects\> php symfony new my_project_name

This command creates a new directory called my_project_name that contains a fresh new project based
on the most recent stable Symfony version available. In addition, the installer checks if your system meets
the technical requirements to execute Symfony applications. If not, you'll see the list of changes needed
to meet those requirements.
For security reasons, all Symfony versions are digitally signed before distributing them. If you want
to verify the integrity of any Symfony version, follow the steps explained in this post2.

If the installer doesn't work for you or doesn't output anything, make sure that the Phar extension3
is installed and enabled on your computer.

Basing your Project on a Specific Symfony Version
In case your project needs to be based on a specific Symfony version, use the optional second argument
of the new command:
Listing 3-5

1
2
3
4
5
6
7
8

# use the most recent version in any Symfony branch
$ symfony new my_project_name 2.8
$ symfony new my_project_name 3.0
# use a specific Symfony version
$ symfony new my_project_name 2.7.3
$ symfony new my_project_name 2.8.1

2. http://fabien.potencier.org/signing-project-releases.html
3. http://php.net/manual/en/intro.phar.php

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9 # use a beta or RC version (useful for testing new Symfony versions)
10 $ symfony new my_project 3.0.0-BETA1
11 $ symfony new my_project 2.7.0-RC1

The installer also supports a special version called lts which installs the most recent Symfony LTS
version available:
Listing 3-6

1 $ symfony new my_project_name lts

Read the Symfony Release process to better understand why there are several Symfony versions and which
one to use for your projects.

Creating Symfony Applications without the Installer
If you still use PHP 5.3, or if you can't execute the installer for any reason, you can create Symfony
applications using the alternative installation method based on Composer4.
Composer is the dependency manager used by modern PHP applications and it can also be used to
create new applications based on the Symfony Framework. If you don't have it installed globally, start by
reading the next section.

Installing Composer Globally
Start with installing Composer globally.

Creating a Symfony Application with Composer
Once Composer is installed on your computer, execute the create-project command to create a new
Symfony application based on its latest stable version:
Listing 3-7

1 $ composer create-project symfony/framework-standard-edition my_project_name

If you need to base your application on a specific Symfony version, provide that version as the second
argument of the create-project command:
Listing 3-8

1 $ composer create-project symfony/framework-standard-edition my_project_name "3.0.*"

If your Internet connection is slow, you may think that Composer is not doing anything. If that's
your case, add the -vvv flag to the previous command to display a detailed output of everything
that Composer is doing.

Running the Symfony Application
Symfony leverages the internal web server provided by PHP to run applications while developing them.
Therefore, running a Symfony application is a matter of browsing the project directory and executing this
command:

4. https://getcomposer.org/

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Listing 3-9

1 $ cd my_project_name/
2 $ php bin/console server:run

Then, open your browser and access the http://localhost:8000/ URL to see the Welcome Page of
Symfony:

Instead of the Welcome Page, you may see a blank page or an error page. This is caused by a directory
permission misconfiguration. There are several possible solutions depending on your operating system.
All of them are explained in the Setting up Permissions section.
PHP's internal web server is available in PHP 5.4 or higher versions. If you still use the legacy PHP
5.3 version, you'll have to configure a virtual host in your web server.

The server:run command is only suitable while developing the application. In order to run Symfony
applications on production servers, you'll have to configure your Apache5 or Nginx6 web server as
explained in Configuring a Web Server.
When you are finished working on your Symfony application, you can stop the server by pressing Ctrl+C
from terminal.

Checking Symfony Application Configuration and Setup
Symfony applications come with a visual server configuration tester to show if your environment is ready
to use Symfony. Access the following URL to check your configuration:
Listing 3-10

1 http://localhost:8000/config.php

If there are any issues, correct them now before moving on.

5. http://httpd.apache.org/docs/current/mod/core.html#documentroot
6. http://wiki.nginx.org/Symfony

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Setting up Permissions
One common issue when installing Symfony is that the var directory must be writable both by the
web server and the command line user. On a UNIX system, if your web server user is different from
your command line user who owns the files, you can try one of the following solutions.
1. Use the same user for the CLI and the web server
In development environments, it is a common practice to use the same UNIX user for the CLI and
the web server because it avoids any of these permissions issues when setting up new projects. This
can be done by editing your web server configuration (e.g. commonly httpd.conf or apache2.conf
for Apache) and setting its user to be the same as your CLI user (e.g. for Apache, update the User
and Group values).
2. Using ACL on a system that supports chmod +a
Many systems allow you to use the chmod +a command. Try this first, and if you get an error try the next method. This uses a command to try to determine your web server user and set it as
HTTPDUSER:
Listing 3-11

1
2
3
4
5

$ rm -rf var/cache/* var/logs/* var/sessions/*
$ HTTPDUSER=`ps axo user,comm | grep -E '[a]pache|[h]ttpd|[_]www|[w]ww-data|[n]ginx'
| grep -v root | head -1 | cut -d\ -f1`
$ sudo chmod -R +a "$HTTPDUSER allow
delete,write,append,file_inherit,directory_inherit" var
$ sudo chmod -R +a "`whoami` allow
delete,write,append,file_inherit,directory_inherit" var

3. Using ACL on a system that does not support chmod +a
Some systems don't support chmod +a, but do support another utility called setfacl. You may
need to enable ACL support7 on your partition and install setfacl before using it (as is the case with
Ubuntu). This uses a command to try to determine your web server user and set it as HTTPDUSER:
Listing 3-12

1 $ HTTPDUSER=`ps axo user,comm | grep -E '[a]pache|[h]ttpd|[_]www|[w]ww-data|[n]ginx'
2 | grep -v root | head -1 | cut -d\ -f1`
3 $ sudo setfacl -R -m u:"$HTTPDUSER":rwX -m u:`whoami`:rwX var
$ sudo setfacl -dR -m u:"$HTTPDUSER":rwX -m u:`whoami`:rwX var

If this doesn't work, try adding -n option.
4. Without using ACL
If none of the previous methods work for you, change the umask so that the cache and log
directories will be group-writable or world-writable (depending if the web server user and the
command line user are in the same group or not). To achieve this, put the following line at the
beginning of the bin/console, web/app.php and web/app_dev.php files:
Listing 3-13

1 umask(0002); // This will let the permissions be 0775
2
3 // or
4
5 umask(0000); // This will let the permissions be 0777

Note that using the ACL is recommended when you have access to them on your server because
changing the umask is not thread-safe.

7. https://help.ubuntu.com/community/FilePermissionsACLs

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Updating Symfony Applications
At this point, you've created a fully-functional Symfony application in which you'll start to develop your
own project. A Symfony application depends on a number of external libraries. These are downloaded
into the vendor/ directory and they are managed exclusively by Composer.
Updating those third-party libraries frequently is a good practice to prevent bugs and security
vulnerabilities. Execute the update Composer command to update them all at once:
Listing 3-14

1 $ cd my_project_name/
2 $ composer update

Depending on the complexity of your project, this update process can take up to several minutes to
complete.
Symfony provides a command to check whether your project's dependencies contain any known
security vulnerability:
Listing 3-15

1 $ php bin/console security:check

A good security practice is to execute this command regularly to be able to update or replace
compromised dependencies as soon as possible.

Installing the Symfony Demo Application
The Symfony Demo application is a fully-functional application that shows the recommended way
to develop Symfony applications. The application has been conceived as a learning tool for Symfony
newcomers and its source code contains tons of comments and helpful notes.
In order to download the Symfony Demo application, execute the demo command of the Symfony
Installer anywhere in your system:
Listing 3-16

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# Linux, Mac OS X
$ symfony demo
# Windows
c:\projects\> php symfony demo

Once downloaded, enter into the symfony_demo/ directory and run the PHP's built-in web server
executing the php bin/console server:run command. Access to the http://localhost:8000 URL in
your browser to start using the Symfony Demo application.

Installing a Symfony Distribution
Symfony project packages "distributions", which are fully-functional applications that include the
Symfony core libraries, a selection of useful bundles, a sensible directory structure and some default
configuration. In fact, when you created a Symfony application in the previous sections, you actually
downloaded the default distribution provided by Symfony, which is called Symfony Standard Edition.
The Symfony Standard Edition is by far the most popular distribution and it's also the best choice
for developers starting with Symfony. However, the Symfony Community has published other popular
distributions that you may use in your applications:

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• The Symfony CMF Standard Edition8 is the best distribution to get started with the Symfony
CMF9 project, which is a project that makes it easier for developers to add CMS functionality
to applications built with the Symfony Framework.
• The Symfony REST Edition10 shows how to build an application that provides a RESTful API
using the FOSRestBundle and several other related bundles.

Using Source Control
If you're using a version control system like Git11, you can safely commit all your project's code. The
reason is that Symfony applications already contain a .gitignore file specially prepared for Symfony.
For specific instructions on how best to set up your project to be stored in Git, see How to Create and
Store a Symfony Project in Git.

Checking out a versioned Symfony Application
When using Composer to manage application's dependencies, it's recommended to ignore the entire
vendor/ directory before committing its code to the repository. This means that when checking out a
Symfony application from a Git repository, there will be no vendor/ directory and the application won't
work out-of-the-box.
In order to make it work, check out the Symfony application and then execute the install Composer
command to download and install all the dependencies required by the application:
Listing 3-17

1 $ cd my_project_name/
2 $ composer install

How does Composer know which specific dependencies to install? Because when a Symfony application
is committed to a repository, the composer.json and composer.lock files are also committed. These
files tell Composer which dependencies (and which specific versions) to install for the application.

Beginning Development
Now that you have a fully-functional Symfony application, you can begin development! Your distribution
may contain some sample code - check the README.md file included with the distribution (open it as a
text file) to learn about what sample code was included with your distribution.
If you're new to Symfony, check out "Create your First Page in Symfony", where you'll learn how to create
pages, change configuration, and do everything else you'll need in your new application.
Be sure to also check out the Cookbook, which contains a wide variety of articles about solving specific
problems with Symfony.

8. https://github.com/symfony-cmf/symfony-cmf-standard
9. http://cmf.symfony.com/
10. https://github.com/gimler/symfony-rest-edition
11. http://git-scm.com/

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Chapter 4

Create your First Page in Symfony
Creating a new page - whether it's an HTML page or a JSON endpoint - is a simple two-step process:
1. Create a route: A route is the URL (e.g. /about) to your page and points to a controller;
2. Create a controller: A controller is the function you write that builds the page. You take the
incoming request information and use it to create a Symfony Response object, which can hold
HTML content, a JSON string or anything else.
Just like on the web, every interaction is initiated by an HTTP request. Your job is pure and simple:
understand that request and return a response.
Do you prefer video tutorials? Check out the Joyful Development with Symfony1 screencast series from
KnpUniversity.

Creating a Page: Route and Controller
Before continuing, make sure you've read the Installation chapter and can access your new
Symfony app in the browser.

Suppose you want to create a page - /lucky/number - that generates a lucky (well, random) number and
prints it. To do that, create a class and a method inside of it that will be executed when someone goes to
/lucky/number:
Listing 4-1

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// src/AppBundle/Controller/LuckyController.php
namespace AppBundle\Controller;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Component\HttpFoundation\Response;
class LuckyController
{

1. http://knpuniversity.com/screencast/symfony/first-page

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9
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20 }

/**
* @Route("/lucky/number")
*/
public function numberAction()
{
$number = rand(0, 100);
return new Response(
'Lucky number: '.$number.''
);
}

Before diving into this, test it out!
http://localhost:8000/lucky/number2

If you set up a proper virtual host in Apache or Nginx, replace http://localhost:8000 with your
host name - like http://symfony.dev/app_dev.php/lucky/number.

If you see a lucky number being printed back to you, congratulations! But before you run off to play the
lottery, check out how this works.
The @Route above numberAction() is called an annotation and it defines the URL pattern. You can also
write routes in YAML (or other formats): read about this in the routing chapter. Actually, most routing
examples in the docs have tabs that show you how each format looks.
The method below the annotation - numberAction - is called the controller and is where you build the
page. The only rule is that a controller must return a Symfony Response object (and you'll even learn to
bend this rule eventually).

Creating a JSON Response
The Response object you return in your controller can contain HTML, JSON or even a binary file like an
image or PDF. You can easily set HTTP headers or the status code.
Suppose you want to create a JSON endpoint that returns the lucky number. Just add a second method
to LuckyController:
Listing 4-2

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// src/AppBundle/Controller/LuckyController.php
// ...
class LuckyController
{
// ...
/**
* @Route("/api/lucky/number")
*/
public function apiNumberAction()
{
$data = array(

2. http://localhost:8000/lucky/number

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14
15
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23 }

'lucky_number' => rand(0, 100),
);
return new Response(
json_encode($data),
200,
array('Content-Type' => 'application/json')
);
}

Try this out in your browser:
http://localhost:8000/api/lucky/number3
You can even shorten this with the handy JsonResponse4:
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// src/AppBundle/Controller/LuckyController.php
// ...
// --> don't forget this new use statement
use Symfony\Component\HttpFoundation\JsonResponse;
class LuckyController
{
// ...

/**
* @Route("/api/lucky/number")
*/
public function apiNumberAction()
{
$data = array(
'lucky_number' => rand(0, 100),
);
// calls json_encode and sets the Content-Type header
return new JsonResponse($data);
}
}

Dynamic URL Patterns: /lucky/number/{count}
Woh, you're doing great! But Symfony's routing can do a lot more. Suppose now that you want a user
to be able to go to /lucky/number/5 to generate 5 lucky numbers at once. Update the route to have a
{wildcard} part at the end:
Listing 4-4

1 // src/AppBundle/Controller/LuckyController.php
2
3 // ...

3. http://localhost:8000/api/lucky/number
4. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/JsonResponse.html

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4 class LuckyController
5 {
6
/**
7
* @Route("/lucky/number/{count}")
8
*/
9
public function numberAction()
10
{
11
// ...
12
}
13
14
// ...
15 }

Because of the {count} "placeholder", the URL to the page is different: it now works for URLs matching
/lucky/number/* - for example /lucky/number/5. The best part is that you can access this value and
use it in your controller:
Listing 4-5

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// src/AppBundle/Controller/LuckyController.php
// ...
class LuckyController
{

/**
* @Route("/lucky/number/{count}")
*/
public function numberAction($count)
{
$numbers = array();
for ($i = 0; $i < $count; $i++) {
$numbers[] = rand(0, 100);
}
$numbersList = implode(', ', $numbers);
return new Response(
'Lucky numbers: '.$numbersList.''
);
}

// ...
}

Try it by going to /lucky/number/XX - replacing XX with any number:
http://localhost:8000/lucky/number/75
You should see 7 lucky numbers printed out! You can get the value of any {placeholder} in your route
by adding a $placeholder argument to your controller. Just make sure they have the same name.
The routing system can do a lot more, like supporting multiple placeholders (e.g. /blog/{category}/
{page})), making placeholders optional and forcing placeholder to match a regular expression (e.g. so
that {count} must be a number).
Find out about all of this and become a routing expert in the Routing chapter.

5. http://localhost:8000/lucky/number/7

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Rendering a Template (with the Service Container)
If you're returning HTML from your controller, you'll probably want to render a template. Fortunately,
Symfony comes with Twig: a templating language that's easy, powerful and actually quite fun.
So far, LuckyController doesn't extend any base class. The easiest way to use Twig - or many other tools
in Symfony - is to extend Symfony's base Controller6 class:
Listing 4-6

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// src/AppBundle/Controller/LuckyController.php
// ...
// --> add this new use statement
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
class LuckyController extends Controller
{
// ...
}

Using the templating Service
This doesn't change anything, but it does give you access to Symfony's container: an array-like object that
gives you access to every useful object in the system. These useful objects are called services, and Symfony
ships with a service object that can render Twig templates, another that can log messages and many more.
To render a Twig template, use a service called templating:
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// src/AppBundle/Controller/LuckyController.php
// ...
class LuckyController extends Controller
{
/**
* @Route("/lucky/number/{count}")
*/
public function numberAction($count)
{
// ...
$numbersList = implode(', ', $numbers);
$html = $this->container->get('templating')->render(
'lucky/number.html.twig',
array('luckyNumberList' => $numbersList)
);
return new Response($html);
}

// ...
}

You'll learn a lot more about the important "service container" as you keep reading. For now, you just
need to know that it holds a lot of objects, and you can get() any object by using its nickname, like
templating or logger. The templating service is an instance of TwigEngine7 and this has a render()
method.
6. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html
7. http://api.symfony.com/3.0/Symfony/Bundle/TwigBundle/TwigEngine.html

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But this can get even easier! By extending the Controller class, you also get a lot of shortcut methods,
like render():
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// src/AppBundle/Controller/LuckyController.php
// ...
/**
* @Route("/lucky/number/{count}")
*/
public function numberAction($count)
{
// ...
/*
$html = $this->container->get('templating')->render(
'lucky/number.html.twig',
array('luckyNumberList' => $numbersList)
);
return new Response($html);
*/
// render: a shortcut that does the same as above
return $this->render(
'lucky/number.html.twig',
array('luckyNumberList' => $numbersList)
);
}

Learn more about these shortcut methods and how they work in the Controller chapter.
For more advanced users, you can also register your controllers as services.

Create the Template
If you refresh now, you'll get an error:
Unable to find template "lucky/number.html.twig"
Fix that by creating a new app/Resources/views/lucky directory and putting a number.html.twig file
inside of it:
Listing 4-9

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{# app/Resources/views/lucky/number.html.twig #}
{% extends 'base.html.twig' %}
{% block body %}

Lucky Numbers: {{ luckyNumberList }}


{% endblock %}

Welcome to Twig! This simple file already shows off the basics: like how the {{ variableName }} syntax
is used to print something. The luckyNumberList is a variable that you're passing into the template from
the render call in your controller.

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The {% extends 'base.html.twig' %} points to a layout file that lives at app/Resources/views/
base.html.twig8 and came with your new project. It's really basic (an unstyled HTML structure) and it's
yours to customize. The {% block body %} part uses Twig's inheritance system to put the content into
the middle of the base.html.twig layout.
Refresh to see your template in action!
http://localhost:8000/lucky/number/99
If you view the source code, you now have a basic HTML structure thanks to base.html.twig.
This is just the surface of Twig's power. When you're ready to master its syntax, loop over arrays, render
other templates and other cool things, read the Templating chapter.

Exploring the Project
You've already created a flexible URL, rendered a template that uses inheritance and created a JSON
endpoint. Nice!
It's time to explore and demystify the files in your project. You've already worked inside the two most
important directories:
app/
Contains things like configuration and templates. Basically, anything that is not PHP code goes here.
src/
Your PHP code lives here.
99% of the time, you'll be working in src/ (PHP files) or app/ (everything else). As you get more
advanced, you'll learn what can be done inside each of these.
The app/ directory also holds some other things, like app/AppKernel.php, which you'll use to enable
new bundles (this is one of a very short list of PHP files in app/).
The src/ directory has just one directory - src/AppBundle - and everything lives inside of it. A bundle
is like a "plugin" and you can find open source bundles10 and install them into your project. But even
your code lives in a bundle - typically AppBundle (though there's nothing special about AppBundle). To
find out more about bundles and why you might create multiple bundles (hint: sharing code between
projects), see the Bundles chapter.
So what about the other directories in the project?
web/
This is the document root for the project and contains any publicly accessible files, like CSS, images
and the Symfony front controllers that execute the app (app_dev.php and app.php).
tests/
The automatic tests (e.g. Unit tests) of your application live here.
bin/
The "binary" files live here. The most important one is the console file which is used to execute
Symfony commands via the console.

8. https://github.com/symfony/symfony-standard/blob/3.0/app/Resources/views/base.html.twig
9. http://localhost:8000/lucky/number/9
10. http://knpbundles.com

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var/
This is where automatically created files are stored, like cache files (var/cache/) and logs (var/
logs/).
vendor/
Third-party libraries, packages and bundles are downloaded here by the Composer11 package
manager. You should never edit something in this directory.
Symfony is flexible. If you need to, you can easily override the default directory structure. See How to Override
Symfony's default Directory Structure.

Application Configuration
Symfony comes with several built-in bundles (open your app/AppKernel.php file) and you'll probably
install more. The main configuration file for bundles is app/config/config.yml:
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# app/config/config.yml
# ...
framework:
secret: '%secret%'
router:
resource: '%kernel.root_dir%/config/routing.yml'
# ...
twig:
debug:
'%kernel.debug%'
strict_variables: '%kernel.debug%'

# ...

The framework key configures FrameworkBundle, the twig key configures TwigBundle and so on. A lot
of behavior in Symfony can be controlled just by changing one option in this configuration file. To find
out how, see the Configuration Reference section.
Or, to get a big example dump of all of the valid configuration under a key, use the handy bin/console
command:
Listing 4-11

1 $ php bin/console config:dump-reference framework

There's a lot more power behind Symfony's configuration system, including environments, imports and
parameters. To learn all of it, see the Configuration chapter.

What's Next?
Congrats! You're already starting to master Symfony and learn a whole new way of building beautiful,
functional, fast and maintainable apps.
Ok, time to finish mastering the fundamentals by reading these chapters:
• Controller
• Routing
11. https://getcomposer.org

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• Creating and Using Templates
Then, in the Symfony Book, learn about the service container, the form system, using Doctrine (if you need
to query a database) and more!
There's also a Cookbook packed with more advanced "how to" articles to solve a lot of problems.
Have fun!

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Chapter 5

Controller
A controller is a PHP callable you create that takes information from the HTTP request and creates and
returns an HTTP response (as a Symfony Response object). The response could be an HTML page, an
XML document, a serialized JSON array, an image, a redirect, a 404 error or anything else you can dream
up. The controller contains whatever arbitrary logic your application needs to render the content of a
page.
See how simple this is by looking at a Symfony controller in action. This renders a page that prints the
famous Hello world!:
Listing 5-1

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use Symfony\Component\HttpFoundation\Response;
public function helloAction()
{
return new Response('Hello world!');
}

The goal of a controller is always the same: create and return a Response object. Along the way, it might
read information from the request, load a database resource, send an email, or set information on the
user's session. But in all cases, the controller will eventually return the Response object that will be
delivered back to the client.
There's no magic and no other requirements to worry about! Here are a few common examples:
• Controller A prepares a Response object representing the content for the homepage of the site.
• Controller B reads the {slug} placeholder from the request to load a blog entry from the
database and creates a Response object displaying that blog. If the {slug} can't be found in
the database, it creates and returns a Response object with a 404 status code.
• Controller C handles the form submission of a contact form. It reads the form information
from the request, saves the contact information to the database and emails the contact
information to you. Finally, it creates a Response object that redirects the client's browser to
the contact form "thank you" page.

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Chapter 5: Controller | 42

Requests, Controller, Response Lifecycle
Every request handled by a Symfony project goes through the same simple lifecycle. The framework takes
care of all the repetitive stuff: you just need to write your custom code in the controller function:
1. Each request executes a single front controller file (e.g. app.php on production or app_dev.php
on development) that bootstraps the application;
2. The front controller's only job is to initialize Symfony's engine (called the Kernel) and pass it a
Request object to handle;
3. The Symfony core asks the router to inspect the request;
4. The router matches the incoming URL to a specific route and returns information about the
route, including the controller that should be executed;
5. The correct controller from the matched route is executed and the code inside the controller
creates and returns the appropriate Response object;
6. The HTTP headers and content of the Response object are sent back to the client.
Creating a page is as easy as creating a controller (#5) and making a route that maps a URL to that
controller (#4).

Though similarly named, a "front controller" is different from the PHP functions called
"controllers" talked about in this chapter. A front controller is a short PHP file that lives in your
web/ directory through which all requests are directed. A typical application will have a production
front controller (e.g. app.php) and a development front controller (e.g. app_dev.php). You'll likely
never need to edit, view or worry about the front controllers in your application. The "controller
class" is a convenient way to group several "controllers", also called actions, together in one class
(e.g. updateAction(), deleteAction(), etc). So, a controller is a method inside a controller class.
They hold your code which creates and returns the appropriate Response object.

A Simple Controller
While a controller can be any PHP callable (a function, method on an object, or a Closure), a controller
is usually a method inside a controller class:
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// src/AppBundle/Controller/HelloController.php
namespace AppBundle\Controller;
use Symfony\Component\HttpFoundation\Response;
class HelloController

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Chapter 5: Controller | 43

7 {
8
9
10
11
12 }

public function indexAction($name)
{
return new Response('Hello '.$name.'!');
}

The controller is the indexAction() method, which lives inside a controller class HelloController.
This controller is pretty straightforward:
• line 2: Symfony takes advantage of PHP's namespace functionality to namespace the entire
controller class.
• line 4: Symfony again takes advantage of PHP's namespace functionality: the use keyword
imports the Response class, which the controller must return.
• line 6: The class name is the concatenation of a name for the controller class (i.e. Hello)
and the word Controller. This is a convention that provides consistency to controllers and
allows them to be referenced only by the first part of the name (i.e. Hello) in the routing
configuration.
• line 8: Each action in a controller class is suffixed with Action and is referenced in the routing
configuration by the action's name (e.g. index). In the next section, you'll create a route
that maps a URI to this action. You'll learn how the route's placeholders ({name}) become
arguments to the controller method ($name).
• line 10: The controller creates and returns a Response object.

Mapping a URL to a Controller
The new controller returns a simple HTML page. To actually view this page in your browser, you need
to create a route, which maps a specific URL path to the controller:
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// src/AppBundle/Controller/HelloController.php
namespace AppBundle\Controller;
use Symfony\Component\HttpFoundation\Response;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
class HelloController
{
/**
* @Route("/hello/{name}", name="hello")
*/
public function indexAction($name)
{
return new Response('Hello '.$name.'!');
}
}

Now, you can go to /hello/ryan (e.g. http://localhost:8000/hello/ryan if you're using the builtin web server) and Symfony will execute the HelloController::indexAction() controller and pass
in ryan for the $name variable. Creating a "page" means simply creating a controller method and an
associated route.
Simple, right?

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Chapter 5: Controller | 44

The AppBundle:Hello:index controller syntax
If you use the YAML or XML formats, you'll refer to the controller using a special shortcut syntax
called the logical controller name which, for example, looks like AppBundle:Hello:index. For
more details on the controller format, read Controller Naming Pattern subtitle of the Routing
chapter.

Route Parameters as Controller Arguments
You already know that the route points to the HelloController::indexAction() controller method
that lives inside AppBundle. What's more interesting is the argument that is passed to that controller
method:
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// src/AppBundle/Controller/HelloController.php
// ...
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
/**
* @Route("/hello/{name}", name="hello")
*/
public function indexAction($name)
{
// ...
}

The controller has a single argument, $name, which corresponds to the {name} placeholder from the
matched route (e.g. ryan if you go to /hello/ryan). When executing the controller, Symfony matches
each argument with a placeholder from the route. So the value for {name} is passed to $name. Just make
sure they the name of the placeholder is the same as the name of the argument variable.
Take the following more-interesting example, where the controller has two arguments:
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// src/AppBundle/Controller/HelloController.php
// ...
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
class HelloController
{
/**
* @Route("/hello/{firstName}/{lastName}", name="hello")
*/
public function indexAction($firstName, $lastName)
{
// ...
}
}

Mapping route parameters to controller arguments is easy and flexible. Keep the following guidelines in
mind while you develop.
1. The order of the controller arguments does not matter

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Chapter 5: Controller | 45

Symfony matches the parameter names from the route to the variable names of the
controller. The arguments of the controller could be totally reordered and still work
perfectly:
Listing 5-6

1 public function indexAction($lastName, $firstName)
2 {
3
// ...
4 }

2. Each required controller argument must match up with a routing parameter
The following would throw a RuntimeException because there is no foo parameter
defined in the route:
Listing 5-7

1 public function indexAction($firstName, $lastName, $foo)
2 {
3
// ...
4 }

Making the argument optional, however, is perfectly ok. The following example would
not throw an exception:
Listing 5-8

1 public function indexAction($firstName, $lastName, $foo = 'bar')
2 {
3
// ...
4 }

3. Not all routing parameters need to be arguments on your controller
If, for example, the lastName weren't important for your controller, you could omit it
entirely:
Listing 5-9

1 public function indexAction($firstName)
2 {
3
// ...
4 }

You can also pass other variables from your route to your controller arguments. See How to Pass
Extra Information from a Route to a Controller.

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Chapter 5: Controller | 46

The Base Controller Class
For convenience, Symfony comes with an optional base Controller1 class. If you extend it, this won't
change anything about how your controller works, but you'll get access to a number of helper methods
and the service container (see Accessing other Services): an array-like object that gives you access to
every useful object in the system. These useful objects are called services, and Symfony ships with a
service object that can render Twig templates, another that can log messages and many more.
Add the use statement atop the Controller class and then modify HelloController to extend it:
Listing 5-10

1
2
3
4
5
6
7
8
9

// src/AppBundle/Controller/HelloController.php
namespace AppBundle\Controller;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
class HelloController extends Controller
{
// ...
}

Helper methods are just shortcuts to using core Symfony functionality that's available to you with or
without the use of the base Controller class. A great way to see the core functionality in action is to look
in the Controller2 class.
If you're curious about how a controller would work that did not extend this base Controller class, check out
cookbook article Controllers as Services. This is optional, but can give you more control over the exact objects/
dependencies that are injected into your controller.

Generating URLs
The generateUrl()3 method is just a helper method that generates the URL for a given route.

Redirecting
If you want to redirect the user to another page, use the redirectToRoute() method:
Listing 5-11

1 public function indexAction()
2 {
3
return $this->redirectToRoute('homepage');
4
5
// redirectToRoute is equivalent to using redirect() and generateUrl() together:
6
// return $this->redirect($this->generateUrl('homepage'));
7 }

New in version 2.6: The redirectToRoute() method was introduced in Symfony 2.6. Previously (and
still now), you could use redirect() and generateUrl() together for this (see the example above).
By default, the redirectToRoute() method performs a 302 (temporary) redirect. To perform a 301
(permanent) redirect, modify the third argument:
Listing 5-12

1 public function indexAction()
2 {

1. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html
2. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html
3. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html#method_generateUrl

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Chapter 5: Controller | 47

3
4 }

return $this->redirectToRoute('homepage', array(), 301);

To redirect to an external site, use redirect() and pass it the external URL:
Listing 5-13

1 public function indexAction()
2 {
3
return $this->redirect('http://symfony.com/doc');
4 }

For more information, see the Routing chapter.
The redirectToRoute() method is simply a shortcut that creates a Response object that
specializes in redirecting the user. It's equivalent to:
Listing 5-14

1
2
3
4
5
6

use Symfony\Component\HttpFoundation\RedirectResponse;
public function indexAction()
{
return new RedirectResponse($this->generateUrl('homepage'));
}

Rendering Templates
If you're serving HTML, you'll want to render a template. The render() method renders a template and
puts that content into a Response object for you:
Listing 5-15

1 // renders app/Resources/views/hello/index.html.twig
2 return $this->render('hello/index.html.twig', array('name' => $name));

Templates can also live in deeper sub-directories. Just try to avoid creating unnecessarily deep structures:
Listing 5-16

1 // renders app/Resources/views/hello/greetings/index.html.twig
2 return $this->render('hello/greetings/index.html.twig', array(
3
'name' => $name
4 ));

Templates are a generic way to render content in any format. And while in most cases you'll use templates
to render HTML content, a template can just as easily generate JavaScript, CSS, XML or any other
format you can dream of. To learn how to render different templating formats read the Template Formats
section of the Creating and Using Templates chapter.
The Symfony templating engine is explained in great detail in the Creating and Using Templates chapter.

Templating Naming Pattern
You can also put templates in the Resources/views directory of a bundle and reference them
with a special shortcut syntax like @AppBundle/Hello/index.html.twig or @AppBundle/
layout.html.twig. These would live in at Resources/views/Hello/index.html.twig and
Resources/views/layout.html.twig inside the bundle respectively.

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Chapter 5: Controller | 48

Accessing other Services
Symfony comes packed with a lot of useful objects, called services. These are used for rendering
templates, sending emails, querying the database and any other "work" you can think of. When you
install a new bundle, it probably brings in even more services.
When extending the base controller class, you can access any Symfony service via the get()4 method of
the Controller class. Here are several common services you might need:
Listing 5-17

1 $templating = $this->get('templating');
2
3 $router = $this->get('router');
4
5 $mailer = $this->get('mailer');

What other services exist? To list all services, use the debug:container console command:
Listing 5-18

1 $ php bin/console debug:container

For more information, see the Service Container chapter.

Managing Errors and 404 Pages
When things are not found, you should play well with the HTTP protocol and return a 404 response. To
do this, you'll throw a special type of exception. If you're extending the base Controller class, do the
following:
Listing 5-19

1 public function indexAction()
2 {
3
// retrieve the object from database
4
$product = ...;
5
if (!$product) {
6
throw $this->createNotFoundException('The product does not exist');
7
}
8
9
return $this->render(...);
10 }

The createNotFoundException()5 method is just a shortcut to create a special
NotFoundHttpException6 object, which ultimately triggers a 404 HTTP response inside Symfony.
Of course, you're free to throw any Exception class in your controller - Symfony will automatically return
a 500 HTTP response code.
Listing 5-20

1 throw new \Exception('Something went wrong!');

In every case, an error page is shown to the end user and a full debug error page is shown to the developer
(i.e. when you're using the app_dev.php front controller - see Environments).
You'll want to customize the error page your user sees. To do that, see the "How to Customize Error
Pages" cookbook recipe.

4. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html#method_get
5. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html#method_createNotFoundException
6. http://api.symfony.com/3.0/Symfony/Component/HttpKernel/Exception/NotFoundHttpException.html

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Chapter 5: Controller | 49

The Request object as a Controller Argument
What if you need to read query parameters, grab a request header or get access to an uploaded file? All
of that information is stored in Symfony's Request object. To get it in your controller, just add it as an
argument and type-hint it with the ``Request`` class:
Listing 5-21

1
2
3
4
5
6
7
8

use Symfony\Component\HttpFoundation\Request;
public function indexAction($firstName, $lastName, Request $request)
{
$page = $request->query->get('page', 1);

// ...
}

Managing the Session
Symfony provides a nice session object that you can use to store information about the user (be it a
real person using a browser, a bot, or a web service) between requests. By default, Symfony stores the
attributes in a cookie by using the native PHP sessions.
To retrieve the session, call getSession()7 method on the Request object. This method returns a
SessionInterface8 with easy methods for storing and fetching things from the session:
Listing 5-22

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

use Symfony\Component\HttpFoundation\Request;
public function indexAction(Request $request)
{
$session = $request->getSession();

// store an attribute for reuse during a later user request
$session->set('foo', 'bar');
// get the attribute set by another controller in another request
$foobar = $session->get('foobar');
// use a default value if the attribute doesn't exist
$filters = $session->get('filters', array());
}

Stored attributes remain in the session for the remainder of that user's session.

Flash Messages
You can also store special messages, called "flash" messages, on the user's session. By design, flash
messages are meant to be used exactly once: they vanish from the session automatically as soon as you
retrieve them. This feature makes "flash" messages particularly great for storing user notifications.
For example, imagine you're processing a form submission:
Listing 5-23

1 use Symfony\Component\HttpFoundation\Request;
2

7. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html#method_getSession
8. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Session/SessionInterface.html

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Chapter 5: Controller | 50

3 public function updateAction(Request $request)
4 {
5
$form = $this->createForm(...);
6
7
$form->handleRequest($request);
8
9
if ($form->isValid()) {
10
// do some sort of processing
11
12
$this->addFlash(
13
'notice',
14
'Your changes were saved!'
15
);
16
17
// $this->addFlash is equivalent to $this->get('session')->getFlashBag()->add
18
19
return $this->redirectToRoute(...);
20
}
21
22
return $this->render(...);
23 }

After processing the request, the controller sets a flash message in the session and then redirects. The
message key (notice in this example) can be anything: you'll use this key to retrieve the message.
In the template of the next page (or even better, in your base layout template), read any flash messages
from the session:
Listing 5-24

1 {% for flash_message in app.session.flashBag.get('notice') %}
2

3
{{ flash_message }}
4

5 {% endfor %}

It's common to use notice, warning and error as the keys of the different types of flash messages,
but you can use any key that fits your needs.

You can use the peek()9 method instead to retrieve the message while keeping it in the bag.

The Request and Response Object
As mentioned earlier, the framework will pass the Request object to any controller argument that is typehinted with the Request class:
Listing 5-25

1 use Symfony\Component\HttpFoundation\Request;
2
3 public function indexAction(Request $request)

9. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Session/Flash/FlashBagInterface.html#method_peek

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Chapter 5: Controller | 51

4 {
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25 }

$request->isXmlHttpRequest(); // is it an Ajax request?
$request->getPreferredLanguage(array('en', 'fr'));

// retrieve GET and POST variables respectively
$request->query->get('page');
$request->request->get('page');
// retrieve SERVER variables
$request->server->get('HTTP_HOST');
// retrieves an instance of UploadedFile identified by foo
$request->files->get('foo');
// retrieve a COOKIE value
$request->cookies->get('PHPSESSID');
// retrieve an HTTP request header, with normalized, lowercase keys
$request->headers->get('host');
$request->headers->get('content_type');

The Request class has several public properties and methods that return any information you need about
the request.
Like the Request, the Response object has also a public headers property. This is a
ResponseHeaderBag10 that has some nice methods for getting and setting response headers. The header
names are normalized so that using Content-Type is equivalent to content-type or even content_type.
The only requirement for a controller is to return a Response object. The Response11 class is an
abstraction around the HTTP response - the text-based message filled with headers and content that's
sent back to the client:
Listing 5-26

1
2
3
4
5
6
7
8

use Symfony\Component\HttpFoundation\Response;

// create a simple Response with a 200 status code (the default)
$response = new Response('Hello '.$name, Response::HTTP_OK);
// create a JSON-response with a 200 status code
$response = new Response(json_encode(array('name' => $name)));
$response->headers->set('Content-Type', 'application/json');

There are also special classes to make certain kinds of responses easier:
• For JSON, there is JsonResponse12. See Creating a JSON Response.
• For files, there is BinaryFileResponse13. See Serving Files.
• For streamed responses, there is StreamedResponse14. See Streaming a Response.
Now that you know the basics you can continue your research on Symfony Request and Response object in
the HttpFoundation component documentation.

10. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/ResponseHeaderBag.html
11. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Response.html
12. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/JsonResponse.html
13. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/BinaryFileResponse.html
14. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/StreamedResponse.html

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Chapter 5: Controller | 52

Creating Static Pages
You can create a static page without even creating a controller (only a route and template are needed).
See cookbook article How to Render a Template without a custom Controller.

Forwarding to Another Controller
Though not very common, you can also forward to another controller internally with the forward()15
method. Instead of redirecting the user's browser, this makes an "internal" sub-request and calls the
defined controller. The forward() method returns the Response object that's returned from that
controller:
Listing 5-27

1 public function indexAction($name)
2 {
3
$response = $this->forward('AppBundle:Something:fancy', array(
4
'name' => $name,
5
'color' => 'green',
6
));
7
8
// ... further modify the response or return it directly
9
10
return $response;
11 }

The array passed to the method becomes the arguments for the resulting controller. The target controller
method might look something like this:
Listing 5-28

1 public function fancyAction($name, $color)
2 {
3
// ... create and return a Response object
4 }

Just like when creating a controller for a route, the order of the arguments of fancyAction() doesn't
matter: the matching is done by name.

Validating a CSRF Token
Sometimes, you want to use CSRF protection in an action where you don't want to use the Symfony Form
component. If, for example, you're doing a DELETE action, you can use the isCsrfTokenValid()16
method to check the CSRF token:
Listing 5-29

1
2
3
4
5
6
7
8

if ($this->isCsrfTokenValid('token_id', $submittedToken)) {
// ... do something, like deleting an object
}

// isCsrfTokenValid() is equivalent to:
// $this->get('security.csrf.token_manager')->isTokenValid(
//
new \Symfony\Component\Security\Csrf\CsrfToken\CsrfToken('token_id', $token)
// );

15. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html#method_forward
16. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html#method_isCsrfTokenValid

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Chapter 5: Controller | 53

Final Thoughts
Whenever you create a page, you'll ultimately need to write some code that contains the logic for that
page. In Symfony, this is called a controller, and it's a PHP function where you can do anything in order
to return the final Response object that will be returned to the user.
To make life easier, you can choose to extend a base Controller class, which contains shortcut methods
for many common controller tasks. For example, since you don't want to put HTML code in your
controller, you can use the render() method to render and return the content from a template.
In other chapters, you'll see how the controller can be used to persist and fetch objects from a database,
process form submissions, handle caching and more.

Learn more from the Cookbook
• How to Customize Error Pages
• How to Define Controllers as Services

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Chapter 5: Controller | 54

Chapter 6

Routing
Beautiful URLs are an absolute must for any serious web application. This means leaving behind ugly
URLs like index.php?article_id=57 in favor of something like /read/intro-to-symfony.
Having flexibility is even more important. What if you need to change the URL of a page from /blog to
/news? How many links should you need to hunt down and update to make the change? If you're using
Symfony's router, the change is simple.
The Symfony router lets you define creative URLs that you map to different areas of your application. By
the end of this chapter, you'll be able to:





Create complex routes that map to controllers
Generate URLs inside templates and controllers
Load routing resources from bundles (or anywhere else)
Debug your routes

Routing in Action
A route is a map from a URL path to a controller. For example, suppose you want to match any URL like
/blog/my-post or /blog/all-about-symfony and send it to a controller that can look up and render
that blog entry. The route is simple:
Listing 6-1

1
2
3
4
5
6
7
8
9
10
11
12
13

// src/AppBundle/Controller/BlogController.php
namespace AppBundle\Controller;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
class BlogController extends Controller
{
/**
* @Route("/blog/{slug}", name="blog_show")
*/
public function showAction($slug)
{

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Chapter 6: Routing | 55

14
15
16 }

// ...
}

The path defined by the blog_show route acts like /blog/* where the wildcard is given the name slug.
For the URL /blog/my-blog-post, the slug variable gets a value of my-blog-post, which is available
for you to use in your controller (keep reading). The blog_show is the internal name of the route, which
doesn't have any meaning yet and just needs to be unique. Later, you'll use it to generate URLs.
If you don't want to use annotations, because you don't like them or because you don't want to
depend on the SensioFrameworkExtraBundle, you can also use Yaml, XML or PHP. In these formats,
the _controller parameter is a special key that tells Symfony which controller should be executed
when a URL matches this route. The _controller string is called the logical name. It follows a pattern
that
points
to
a
specific
PHP
class
and
method,
in
this
case
the
AppBundle\Controller\BlogController::showAction method.
Congratulations! You've just created your first route and connected it to a controller. Now, when you
visit /blog/my-post, the showAction controller will be executed and the $slug variable will be equal to
my-post.
This is the goal of the Symfony router: to map the URL of a request to a controller. Along the way, you'll
learn all sorts of tricks that make mapping even the most complex URLs easy.

Routing: Under the Hood
When a request is made to your application, it contains an address to the exact "resource" that the
client is requesting. This address is called the URL, (or URI), and could be /contact, /blog/read-me, or
anything else. Take the following HTTP request for example:
Listing 6-2

1 GET /blog/my-blog-post

The goal of the Symfony routing system is to parse this URL and determine which controller should be
executed. The whole process looks like this:
1. The request is handled by the Symfony front controller (e.g. app.php);
2. The Symfony core (i.e. Kernel) asks the router to inspect the request;
3. The router matches the incoming URL to a specific route and returns information about the
route, including the controller that should be executed;
4. The Symfony Kernel executes the controller, which ultimately returns a Response object.

The routing layer is a tool that translates the incoming URL into a specific controller to execute.

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Chapter 6: Routing | 56

Creating Routes
Symfony loads all the routes for your application from a single routing configuration file. The file is
usually app/config/routing.yml, but can be configured to be anything (including an XML or PHP file)
via the application configuration file:
Listing 6-3

1 # app/config/config.yml
2 framework:
3
# ...
4
router: { resource: '%kernel.root_dir%/config/routing.yml' }

Even though all routes are loaded from a single file, it's common practice to include additional
routing resources. To do so, just point out in the main routing configuration file which external
files should be included. See the Including External Routing Resources section for more
information.

Basic Route Configuration
Defining a route is easy, and a typical application will have lots of routes. A basic route consists of just
two parts: the path to match and a defaults array:
Listing 6-4

1
2
3
4
5
6
7
8
9
10
11
12
13

// src/AppBundle/Controller/MainController.php
// ...
class MainController extends Controller
{
/**
* @Route("/")
*/
public function homepageAction()
{
// ...
}
}

This route matches the homepage (/) and maps it to the AppBundle:Main:homepage controller. The
_controller string is translated by Symfony into an actual PHP function and executed. That process will
be explained shortly in the Controller Naming Pattern section.

Routing with Placeholders
Of course the routing system supports much more interesting routes. Many routes will contain one or
more named "wildcard" placeholders:
Listing 6-5

1
2
3
4
5
6
7
8
9

// src/AppBundle/Controller/BlogController.php
// ...
class BlogController extends Controller
{
/**
* @Route("/blog/{slug}")
*/
public function showAction($slug)

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Chapter 6: Routing | 57

10
11
12
13 }

{

// ...
}

The path will match anything that looks like /blog/*. Even better, the value matching the {slug}
placeholder will be available inside your controller. In other words, if the URL is /blog/hello-world,
a $slug variable, with a value of hello-world, will be available in the controller. This can be used, for
example, to load the blog post matching that string.
The path will not, however, match simply /blog. That's because, by default, all placeholders are required.
This can be changed by adding a placeholder value to the defaults array.

Required and Optional Placeholders
To make things more exciting, add a new route that displays a list of all the available blog posts for this
imaginary blog application:
Listing 6-6

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

// src/AppBundle/Controller/BlogController.php
// ...
class BlogController extends Controller
{
// ...
/**
* @Route("/blog")
*/
public function indexAction()
{
// ...
}
}

So far, this route is as simple as possible - it contains no placeholders and will only match the exact URL
/blog. But what if you need this route to support pagination, where /blog/2 displays the second page of
blog entries? Update the route to have a new {page} placeholder:
Listing 6-7

1
2
3
4
5
6
7
8
9
10
11

// src/AppBundle/Controller/BlogController.php
// ...
/**
* @Route("/blog/{page}")
*/
public function indexAction($page)
{
// ...
}

Like the {slug} placeholder before, the value matching {page} will be available inside your controller.
Its value can be used to determine which set of blog posts to display for the given page.
But hold on! Since placeholders are required by default, this route will no longer match on simply /blog.
Instead, to see page 1 of the blog, you'd need to use the URL /blog/1! Since that's no way for a rich web
app to behave, modify the route to make the {page} parameter optional. This is done by including it in
the defaults collection:
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Chapter 6: Routing | 58

Listing 6-8

1
2
3
4
5
6
7
8
9
10
11

// src/AppBundle/Controller/BlogController.php
// ...
/**
* @Route("/blog/{page}", defaults={"page" = 1})
*/
public function indexAction($page)
{
// ...
}

By adding page to the defaults key, the {page} placeholder is no longer required. The URL /blog will
match this route and the value of the page parameter will be set to 1. The URL /blog/2 will also match,
giving the page parameter a value of 2. Perfect.
URL

Route Parameters

/blog

blog

{page} = 1

/blog/1

blog

{page} = 1

/blog/2

blog

{page} = 2

Of course, you can have more than one optional placeholder (e.g. /blog/{slug}/{page}), but
everything after an optional placeholder must be optional. For example, /{page}/blog is a valid
path, but page will always be required (i.e. simply /blog will not match this route).

Routes with optional parameters at the end will not match on requests with a trailing slash (i.e.
/blog/ will not match, /blog will match).

Adding Requirements
Take a quick look at the routes that have been created so far:
Listing 6-9

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

// src/AppBundle/Controller/BlogController.php
// ...
class BlogController extends Controller
{
/**
* @Route("/blog/{page}", defaults={"page" = 1})
*/
public function indexAction($page)
{
// ...
}
/**
* @Route("/blog/{slug}")
*/
public function showAction($slug)
{

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Chapter 6: Routing | 59

19
20
21 }

// ...
}

Can you spot the problem? Notice that both routes have patterns that match URLs that look like
/blog/*. The Symfony router will always choose the first matching route it finds. In other words, the
blog_show route will never be matched. Instead, a URL like /blog/my-blog-post will match the first
route (blog) and return a nonsense value of my-blog-post to the {page} parameter.
URL

Route Parameters

/blog/2

blog

/blog/my-blog-post blog

{page} = 2
{page} = "my-blog-post"

The answer to the problem is to add route requirements or route conditions (see Completely Customized
Route Matching with Conditions). The routes in this example would work perfectly if the /blog/
{page} path only matched URLs where the {page} portion is an integer. Fortunately, regular expression
requirements can easily be added for each parameter. For example:
Listing 6-10

1
2
3
4
5
6
7
8
9
10
11
12
13

// src/AppBundle/Controller/BlogController.php
// ...
/**
* @Route("/blog/{page}", defaults={"page": 1}, requirements={
*
"page": "\d+"
* })
*/
public function indexAction($page)
{
// ...
}

The \d+ requirement is a regular expression that says that the value of the {page} parameter must be a
digit (i.e. a number). The blog route will still match on a URL like /blog/2 (because 2 is a number), but
it will no longer match a URL like /blog/my-blog-post (because my-blog-post is not a number).
As a result, a URL like /blog/my-blog-post will now properly match the blog_show route.
URL

Route

Parameters

/blog/2

blog

{page} = 2

/blog/my-blog-post

blog_show

{slug} = my-blog-post

/blog/2-my-blog-post blog_show

{slug} = 2-my-blog-post

Earlier Routes always Win
What this all means is that the order of the routes is very important. If the blog_show route were
placed above the blog route, the URL /blog/2 would match blog_show instead of blog since
the {slug} parameter of blog_show has no requirements. By using proper ordering and clever
requirements, you can accomplish just about anything.

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Chapter 6: Routing | 60

Since the parameter requirements are regular expressions, the complexity and flexibility of each
requirement is entirely up to you. Suppose the homepage of your application is available in two different
languages, based on the URL:
Listing 6-11

1
2
3
4
5
6
7
8
9
10
11
12
13
14

// src/AppBundle/Controller/MainController.php
// ...
class MainController extends Controller
{
/**
* @Route("/{_locale}", defaults={"_locale": "en"}, requirements={
*
"_locale": "en|fr"
* })
*/
public function homepageAction($_locale)
{
}
}

For incoming requests, the {_locale} portion of the URL is matched against the regular expression
(en|fr).
Path

Parameters

/

{_locale} = "en"

/en

{_locale} = "en"

/fr

{_locale} = "fr"

/es

won't match this route

Adding HTTP Method Requirements
In addition to the URL, you can also match on the method of the incoming request (i.e. GET, HEAD,
POST, PUT, DELETE). Suppose you create an API for your blog and you have 2 routes: One for
displaying a post (on a GET or HEAD request) and one for updating a post (on a PUT request). This can
be accomplished with the following route configuration:
Listing 6-12

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

// src/AppBundle/Controller/MainController.php
namespace AppBundle\Controller;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method;
// ...
class BlogApiController extends Controller
{
/**
* @Route("/api/posts/{id}")
* @Method({"GET","HEAD"})
*/
public function showAction($id)
{
// ... return a JSON response with the post
}

/**
* @Route("/api/posts/{id}")

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Chapter 6: Routing | 61

20
21
22
23
24
25
26 }

* @Method("PUT")
*/
public function editAction($id)
{
// ... edit a post
}

Despite the fact that these two routes have identical paths (/api/posts/{id}), the first route will match
only GET or HEAD requests and the second route will match only PUT requests. This means that you
can display and edit the post with the same URL, while using distinct controllers for the two actions.
If no methods are specified, the route will match on all methods.

Adding a Host Requirement
You can also match on the HTTP host of the incoming request. For more information, see How to Match
a Route Based on the Host in the Routing component documentation.

Completely Customized Route Matching with Conditions
As you've seen, a route can be made to match only certain routing wildcards (via regular expressions),
HTTP methods, or host names. But the routing system can be extended to have an almost infinite
flexibility using conditions:
Listing 6-13

1 contact:
2
path:
/contact
3
defaults: { _controller: AcmeDemoBundle:Main:contact }
4
condition: "context.getMethod() in ['GET', 'HEAD'] and
request.headers.get('User-Agent') matches '/firefox/i'"

The condition is an expression, and you can learn more about its syntax here: The Expression Syntax.
With this, the route won't match unless the HTTP method is either GET or HEAD and if the User-Agent
header matches firefox.
You can do any complex logic you need in the expression by leveraging two variables that are passed into
the expression:
context
An instance of RequestContext1, which holds the most fundamental information about the route
being matched.
request
The Symfony Request2 object (see Request).

Conditions are not taken into account when generating a URL.

1. http://api.symfony.com/3.0/Symfony/Component/Routing/RequestContext.html
2. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Request.html

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Expressions are Compiled to PHP
Behind the scenes, expressions are compiled down to raw PHP. Our example would generate the
following PHP in the cache directory:
Listing 6-14

1 if (rtrim($pathinfo, '/contact') === '' && (
2
in_array($context->getMethod(), array(0 => "GET", 1 => "HEAD"))
3
&& preg_match("/firefox/i", $request->headers->get("User-Agent"))
4 )) {
5
// ...
6 }

Because of this, using the condition key causes no extra overhead beyond the time it takes for the
underlying PHP to execute.

Advanced Routing Example
At this point, you have everything you need to create a powerful routing structure in Symfony. The
following is an example of just how flexible the routing system can be:
Listing 6-15

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

// src/AppBundle/Controller/ArticleController.php
// ...
class ArticleController extends Controller
{
/**
* @Route(
*
"/articles/{_locale}/{year}/{title}.{_format}",
*
defaults={"_format": "html"},
*
requirements={
*
"_locale": "en|fr",
*
"_format": "html|rss",
*
"year": "\d+"
*
}
* )
*/
public function showAction($_locale, $year, $title)
{
}
}

As you've seen, this route will only match if the {_locale} portion of the URL is either en or fr and if
the {year} is a number. This route also shows how you can use a dot between placeholders instead of a
slash. URLs matching this route might look like:
• /articles/en/2010/my-post
• /articles/fr/2010/my-post.rss
• /articles/en/2013/my-latest-post.html

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Chapter 6: Routing | 63

The Special _format Routing Parameter
This example also highlights the special _format routing parameter. When using this parameter,
the matched value becomes the "request format" of the Request object.
Ultimately, the request format is used for such things as setting the Content-Type of the response
(e.g. a json request format translates into a Content-Type of application/json). It can also
be used in the controller to render a different template for each value of _format. The _format
parameter is a very powerful way to render the same content in different formats.
In Symfony versions previous to 3.0, it is possible to override the request format by adding a query
parameter named _format (for example: /foo/bar?_format=json). Relying on this behavior not
only is considered a bad practice but it will complicate the upgrade of your applications to Symfony
3.

Sometimes you want to make certain parts of your routes globally configurable. Symfony provides
you with a way to do this by leveraging service container parameters. Read more about this in
"How to Use Service Container Parameters in your Routes".

Special Routing Parameters
As you've seen, each routing parameter or default value is eventually available as an argument in the
controller method. Additionally, there are three parameters that are special: each adds a unique piece of
functionality inside your application:
_controller
As you've seen, this parameter is used to determine which controller is executed when the route is
matched.
_format
Used to set the request format (read more).
_locale
Used to set the locale on the request (read more).

Controller Naming Pattern
Every route must have a _controller parameter, which dictates which controller should be executed
when that route is matched. This parameter uses a simple string pattern called the logical controller name,
which Symfony maps to a specific PHP method and class. The pattern has three parts, each separated by
a colon:
bundle:controller:action
For example, a _controller value of AppBundle:Blog:show means:
Bundle

Controller Class

AppBundle BlogController

Method Name
showAction

The controller might look like this:
Listing 6-16

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1
2
3
4
5
6
7
8
9
10
11
12

// src/AppBundle/Controller/BlogController.php
namespace AppBundle\Controller;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
class BlogController extends Controller
{
public function showAction($slug)
{
// ...
}
}

Notice that Symfony adds the string Controller to the class name (Blog => BlogController) and
Action to the method name (show => showAction).
You could also refer to this controller using its fully-qualified class name and method:
AppBundle\Controller\BlogController::showAction. But if you follow some simple conventions, the
logical name is more concise and allows more flexibility.
In addition to using the logical name or the fully-qualified class name, Symfony supports a
third way of referring to a controller. This method uses just one colon separator (e.g.
service_name:indexAction) and refers to the controller as a service (see How to Define
Controllers as Services).

Route Parameters and Controller Arguments
The route parameters (e.g. {slug}) are especially important because each is made available as an
argument to the controller method:
Listing 6-17

1 public function showAction($slug)
2 {
3
// ...
4 }

In reality, the entire defaults collection is merged with the parameter values to form a single array. Each
key of that array is available as an argument on the controller.
In other words, for each argument of your controller method, Symfony looks for a route parameter of
that name and assigns its value to that argument. In the advanced example above, any combination (in
any order) of the following variables could be used as arguments to the showAction() method:







$_locale
$year
$title
$_format
$_controller
$_route

Since the placeholders and defaults collection are merged together, even the $_controller variable is
available. For a more detailed discussion, see Route Parameters as Controller Arguments.

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Chapter 6: Routing | 65

The special $_route variable is set to the name of the route that was matched.

You can even add extra information to your route definition and access it within your controller. For
more information on this topic, see How to Pass Extra Information from a Route to a Controller.

Including External Routing Resources
All routes are loaded via a single configuration file - usually app/config/routing.yml (see Creating
Routes above). However, if you use routing annotations, you'll need to point the router to the controllers
with the annotations. This can be done by "importing" directories into the routing configuration:
Listing 6-18

1 # app/config/routing.yml
2 app:
3
resource: '@AppBundle/Controller/'
4
type:
annotation # required to enable the Annotation reader for this resource

When importing resources from YAML, the key (e.g. app) is meaningless. Just be sure that it's
unique so no other lines override it.

The resource key loads the given routing resource. In this example the resource is a directory, where the
@AppBundle shortcut syntax resolves to the full path of the AppBundle. When pointing to a directory, all
files in that directory are parsed and put into the routing.
You can also include other routing configuration files, this is often used to import the routing of
third party bundles:
Listing 6-19

1 # app/config/routing.yml
2 app:
3
resource: '@AcmeOtherBundle/Resources/config/routing.yml'

Prefixing Imported Routes
You can also choose to provide a "prefix" for the imported routes. For example, suppose you want to
prefix all routes in the AppBundle with /site (e.g. /site/blog/{slug} instead of /blog/{slug}):
Listing 6-20

1 # app/config/routing.yml
2 app:
3
resource: '@AppBundle/Controller/'
4
type:
annotation
5
prefix:
/site

The path of each route being loaded from the new routing resource will now be prefixed with the string
/site.

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Adding a Host Requirement to Imported Routes
You can set the host regex on imported routes. For more information, see Using Host Matching of
Imported Routes.

Visualizing & Debugging Routes
While adding and customizing routes, it's helpful to be able to visualize and get detailed information
about your routes. A great way to see every route in your application is via the debug:router console
command. Execute the command by running the following from the root of your project.
Listing 6-21

1 $ php bin/console debug:router

This command will print a helpful list of all the configured routes in your application:
Listing 6-22

1
2
3
4
5
6

homepage
contact
contact_process
article_show
blog
blog_show

ANY
GET
POST
ANY
ANY
ANY

/
/contact
/contact
/articles/{_locale}/{year}/{title}.{_format}
/blog/{page}
/blog/{slug}

You can also get very specific information on a single route by including the route name after the
command:
Listing 6-23

1 $ php bin/console debug:router article_show

Likewise, if you want to test whether a URL matches a given route, you can use the router:match
console command:
Listing 6-24

1 $ php bin/console router:match /blog/my-latest-post

This command will print which route the URL matches.
Listing 6-25

1 Route "blog_show" matches

Generating URLs
The routing system should also be used to generate URLs. In reality, routing is a bidirectional system:
mapping the URL to a controller+parameters and a route+parameters back to a URL. The match()3 and
generate()4 methods form this bidirectional system. Take the blog_show example route from earlier:
Listing 6-26

1
2
3
4
5
6

$params = $this->get('router')->match('/blog/my-blog-post');
// array(
//
'slug'
=> 'my-blog-post',
//
'_controller' => 'AppBundle:Blog:show',
// )

3. http://api.symfony.com/3.0/Symfony/Component/Routing/Router.html#method_match
4. http://api.symfony.com/3.0/Symfony/Component/Routing/Router.html#method_generate

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Chapter 6: Routing | 67

7 $uri = $this->get('router')->generate('blog_show', array(
8
'slug' => 'my-blog-post'
9 ));
10 // /blog/my-blog-post

To generate a URL, you need to specify the name of the route (e.g. blog_show) and any wildcards (e.g.
slug = my-blog-post) used in the path for that route. With this information, any URL can easily be
generated:
Listing 6-27

1 class MainController extends Controller
2 {
3
public function showAction($slug)
4
{
5
// ...
6
7
$url = $this->generateUrl(
8
'blog_show',
9
array('slug' => 'my-blog-post')
10
);
11
}
12 }

The generateUrl() method defined in the base Controller5 class is just a shortcut for this code:
Listing 6-28

1 $url = $this->container->get('router')->generate(
2
'blog_show',
3
array('slug' => 'my-blog-post')
4 );

In an upcoming section, you'll learn how to generate URLs from inside templates.
If the front-end of your application uses Ajax requests, you might want to be able to generate URLs
in JavaScript based on your routing configuration. By using the FOSJsRoutingBundle6, you can do
exactly that:
Listing 6-29

1 var url = Routing.generate(
2
'blog_show',
3
{"slug": 'my-blog-post'}
4 );

For more information, see the documentation for that bundle.

Generating URLs with Query Strings
The generate method takes an array of wildcard values to generate the URI. But if you pass extra ones,
they will be added to the URI as a query string:
Listing 6-30

5. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html
6. https://github.com/FriendsOfSymfony/FOSJsRoutingBundle

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1 $this->get('router')->generate('blog', array(
2
'page' => 2,
3
'category' => 'Symfony'
4 ));
5 // /blog/2?category=Symfony

Generating URLs from a Template
The most common place to generate a URL is from within a template when linking between pages in
your application. This is done just as before, but using a template helper function:
Listing 6-31

1
2
Read this blog post.
3


Generating Absolute URLs
By default, the router will generate relative URLs (e.g. /blog). From a controller, simply pass
UrlGeneratorInterface::ABSOLUTE_URL to the third argument of the generateUrl() method:
Listing 6-32

1 use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
2
3 $this->generateUrl('blog_show', array('slug' => 'my-blog-post'),
4 UrlGeneratorInterface::ABSOLUTE_URL);
// http://www.example.com/blog/my-blog-post

From a template, simply use the url() function (which generates an absolute URL) rather than the
path() function (which generates a relative URL):
Listing 6-33

1
2
Read this blog post.
3


The host that's used when generating an absolute URL is automatically detected using the current
Request object. When generating absolute URLs from outside the web context (for instance in a
console command) this doesn't work. See How to Generate URLs from the Console to learn how to
solve this problem.

Summary
Routing is a system for mapping the URL of incoming requests to the controller function that should be
called to process the request. It both allows you to specify beautiful URLs and keeps the functionality
of your application decoupled from those URLs. Routing is a bidirectional mechanism, meaning that it
should also be used to generate URLs.

Learn more from the Cookbook
• How to Force Routes to always Use HTTPS or HTTP
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How to Allow a "/" Character in a Route Parameter
How to Configure a Redirect without a custom Controller
How to Use HTTP Methods beyond GET and POST in Routes
How to Use Service Container Parameters in your Routes
How to Create a custom Route Loader
Redirect URLs with a Trailing Slash
How to Pass Extra Information from a Route to a Controller

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Chapter 6: Routing | 70

Chapter 7

Creating and Using Templates
As you know, the controller is responsible for handling each request that comes into a Symfony
application. In reality, the controller delegates most of the heavy work to other places so that code can
be tested and reused. When a controller needs to generate HTML, CSS or any other content, it hands
the work off to the templating engine. In this chapter, you'll learn how to write powerful templates that
can be used to return content to the user, populate email bodies, and more. You'll learn shortcuts, clever
ways to extend templates and how to reuse template code.
How to render templates is covered in the controller page of the book.

Templates
A template is simply a text file that can generate any text-based format (HTML, XML, CSV, LaTeX ...).
The most familiar type of template is a PHP template - a text file parsed by PHP that contains a mix of
text and PHP code:
Listing 7-1

1
2
3

4
Welcome to Symfony!
5

6

7


8
9

18

19

But Symfony packages an even more powerful templating language called Twig1. Twig allows you to write
concise, readable templates that are more friendly to web designers and, in several ways, more powerful
than PHP templates:
Listing 7-2

1
2
3

4
Welcome to Symfony!
5

6

7

{{ page_title }}


8
9

14

15

Twig defines three types of special syntax:
{{ ... }}
"Says something": prints a variable or the result of an expression to the template.
{% ... %}
"Does something": a tag that controls the logic of the template; it is used to execute statements such
as for-loops for example.
{# ... #}
"Comment something": it's the equivalent of the PHP /* comment */ syntax. It's used to add single
or multi-line comments. The content of the comments isn't included in the rendered pages.
Twig also contains filters, which modify content before being rendered. The following makes the title
variable all uppercase before rendering it:
Listing 7-3

1 {{ title|upper }}

Twig comes with a long list of tags2 and filters3 that are available by default. You can even add your own
extensions4 to Twig as needed.
Registering a Twig extension is as easy as creating a new service and tagging it with
twig.extension tag.

1. http://twig.sensiolabs.org
2. http://twig.sensiolabs.org/doc/tags/index.html
3. http://twig.sensiolabs.org/doc/filters/index.html
4. http://twig.sensiolabs.org/doc/advanced.html#creating-an-extension

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As you'll see throughout the documentation, Twig also supports functions and new functions can be
easily added. For example, the following uses a standard for tag and the cycle function to print ten div
tags, with alternating odd, even classes:
Listing 7-4

1 {% for i in 0..10 %}
2

3

4

5 {% endfor %}

Throughout this chapter, template examples will be shown in both Twig and PHP.
If you do choose to not use Twig and you disable it, you'll need to implement your own exception
handler via the kernel.exception event.

Why Twig?
Twig templates are meant to be simple and won't process PHP tags. This is by design: the Twig
template system is meant to express presentation, not program logic. The more you use Twig, the
more you'll appreciate and benefit from this distinction. And of course, you'll be loved by web
designers everywhere.
Twig can also do things that PHP can't, such as whitespace control, sandboxing, automatic HTML
escaping, manual contextual output escaping, and the inclusion of custom functions and filters
that only affect templates. Twig contains little features that make writing templates easier and more
concise. Take the following example, which combines a loop with a logical if statement:
Listing 7-5

1

    2
    {% for user in users if user.active %}
    3
  • {{ user.username }}

  • 4
    {% else %}
    5
  • No users found

  • 6
    {% endfor %}
    7


Twig Template Caching
Twig is fast. Each Twig template is compiled down to a native PHP class that is rendered at runtime. The
compiled classes are located in the var/cache/{environment}/twig directory (where {environment}
is the environment, such as dev or prod) and in some cases can be useful while debugging. See
Environments for more information on environments.
When debug mode is enabled (common in the dev environment), a Twig template will be automatically
recompiled when changes are made to it. This means that during development you can happily make
changes to a Twig template and instantly see the changes without needing to worry about clearing any
cache.
When debug mode is disabled (common in the prod environment), however, you must clear the Twig
cache directory so that the Twig templates will regenerate. Remember to do this when deploying your
application.

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Template Inheritance and Layouts
More often than not, templates in a project share common elements, like the header, footer, sidebar or
more. In Symfony, this problem is thought about differently: a template can be decorated by another
one. This works exactly the same as PHP classes: template inheritance allows you to build a base "layout"
template that contains all the common elements of your site defined as blocks (think "PHP class with
base methods"). A child template can extend the base layout and override any of its blocks (think "PHP
subclass that overrides certain methods of its parent class").
First, build a base layout file:
Listing 7-6

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

{# app/Resources/views/base.html.twig #}




{% block title %}Test Application{% endblock %}




{% block body %}{% endblock %}




Though the discussion about template inheritance will be in terms of Twig, the philosophy is the
same between Twig and PHP templates.

This template defines the base HTML skeleton document of a simple two-column page. In this example,
three {% block %} areas are defined (title, sidebar and body). Each block may be overridden by a child
template or left with its default implementation. This template could also be rendered directly. In that
case the title, sidebar and body blocks would simply retain the default values used in this template.
A child template might look like this:
Listing 7-7

1
2
3
4
5
6
7
8
9
10
11

{# app/Resources/views/blog/index.html.twig #}
{% extends 'base.html.twig' %}
{% block title %}My cool blog posts{% endblock %}
{% block body %}
{% for entry in blog_entries %}

{{ entry.title }}


{{ entry.body }}


{% endfor %}
{% endblock %}

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The parent template is identified by a special string syntax (base.html.twig). This path is relative
to the app/Resources/views directory of the project. You could also use the logical name
equivalent: ::base.html.twig. This naming convention is explained fully in Template Naming
and Locations.

The key to template inheritance is the {% extends %} tag. This tells the templating engine to first
evaluate the base template, which sets up the layout and defines several blocks. The child template is
then rendered, at which point the title and body blocks of the parent are replaced by those from the
child. Depending on the value of blog_entries, the output might look like this:
Listing 7-8

1
2
3

4

5
My cool blog posts
6

7

8

14
15

16

My first post


17

The body of the first post.


18
19

Another post


20

The body of the second post.


21

22

23

Notice that since the child template didn't define a sidebar block, the value from the parent template is
used instead. Content within a {% block %} tag in a parent template is always used by default.
You can use as many levels of inheritance as you want. In the next section, a common three-level
inheritance model will be explained along with how templates are organized inside a Symfony project.
When working with template inheritance, here are some tips to keep in mind:
• If you use {% extends %} in a template, it must be the first tag in that template;
• The more {% block %} tags you have in your base templates, the better. Remember, child
templates don't have to define all parent blocks, so create as many blocks in your base
templates as you want and give each a sensible default. The more blocks your base templates
have, the more flexible your layout will be;
• If you find yourself duplicating content in a number of templates, it probably means you
should move that content to a {% block %} in a parent template. In some cases, a better
solution may be to move the content to a new template and include it (see Including other
Templates);
• If you need to get the content of a block from the parent template, you can use the {{
parent() }} function. This is useful if you want to add to the contents of a parent block
instead of completely overriding it:
Listing 7-9

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Chapter 7: Creating and Using Templates | 75

1 {% block sidebar %}
2

Table of Contents


3
4
{# ... #}
5
6
{{ parent() }}
7 {% endblock %}

Template Naming and Locations
By default, templates can live in two different locations:
app/Resources/views/
The application's views directory can contain application-wide base templates (i.e. your
application's layouts and templates of the application bundle) as well as templates that override
third party bundle templates (see Overriding Bundle Templates).
path/to/bundle/Resources/views/
Each third party bundle houses its templates in its Resources/views/ directory (and
subdirectories). When you plan to share your bundle, you should put the templates in the bundle
instead of the app/ directory.
Most of the templates you'll use live in the app/Resources/views/ directory. The path you'll use will be
relative to this directory. For example, to render/extend app/Resources/views/base.html.twig, you'll
use the base.html.twig path and to render/extend app/Resources/views/blog/index.html.twig,
you'll use the blog/index.html.twig path.

Referencing Templates in a Bundle
Symfony uses a bundle:directory:filename string syntax for templates that live inside a bundle. This
allows for several types of templates, each which lives in a specific location:
• AcmeBlogBundle:Blog:index.html.twig: This syntax is used to specify a template for a
specific page. The three parts of the string, each separated by a colon (:), mean the following:
• AcmeBlogBundle: (bundle) the template lives inside the AcmeBlogBundle (e.g. src/
Acme/BlogBundle);
• Blog: (directory) indicates that the template lives inside the Blog subdirectory of
Resources/views;
• index.html.twig: (filename) the actual name of the file is index.html.twig.
Assuming that the AcmeBlogBundle lives at src/Acme/BlogBundle, the final path to the layout
would be src/Acme/BlogBundle/Resources/views/Blog/index.html.twig.
• AcmeBlogBundle::layout.html.twig: This syntax refers to a base template that's specific to
the AcmeBlogBundle. Since the middle, "directory", portion is missing (e.g. Blog), the template
lives at Resources/views/layout.html.twig inside AcmeBlogBundle. Yes, there are 2 colons
in the middle of the string when the "controller" subdirectory part is missing.
In the Overriding Bundle Templates section, you'll find out how each template living inside the
AcmeBlogBundle, for example, can be overridden by placing a template of the same name in the app/
Resources/AcmeBlogBundle/views/ directory. This gives the power to override templates from any
vendor bundle.

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Hopefully the template naming syntax looks familiar - it's similar to the naming convention used
to refer to Controller Naming Pattern.

Template Suffix
Every template name also has two extensions that specify the format and engine for that template.
Filename

Format Engine

blog/index.html.twig

HTML

Twig

blog/index.html.php

HTML

PHP

blog/index.css.twig

CSS

Twig

By default, any Symfony template can be written in either Twig or PHP, and the last part of the extension
(e.g. .twig or .php) specifies which of these two engines should be used. The first part of the extension,
(e.g. .html, .css, etc) is the final format that the template will generate. Unlike the engine, which
determines how Symfony parses the template, this is simply an organizational tactic used in case the
same resource needs to be rendered as HTML (index.html.twig), XML (index.xml.twig), or any other
format. For more information, read the Template Formats section.
The available "engines" can be configured and even new engines added. See Templating
Configuration for more details.

Tags and Helpers
You already understand the basics of templates, how they're named and how to use template inheritance.
The hardest parts are already behind you. In this section, you'll learn about a large group of tools available
to help perform the most common template tasks such as including other templates, linking to pages and
including images.
Symfony comes bundled with several specialized Twig tags and functions that ease the work of the
template designer. In PHP, the templating system provides an extensible helper system that provides
useful features in a template context.
You've already seen a few built-in Twig tags ({% block %} & {% extends %}) as well as an example of a
PHP helper ($view['slots']). Here you will learn a few more.

Including other Templates
You'll often want to include the same template or code fragment on several pages. For example, in an
application with "news articles", the template code displaying an article might be used on the article detail
page, on a page displaying the most popular articles, or in a list of the latest articles.
When you need to reuse a chunk of PHP code, you typically move the code to a new PHP class or
function. The same is true for templates. By moving the reused template code into its own template, it
can be included from any other template. First, create the template that you'll need to reuse.
Listing 7-10

1 {# app/Resources/views/article/article_details.html.twig #}
2

{{ article.title }}



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3
4
5


6
{{ article.body }}
7



Including this template from any other template is simple:
Listing 7-11

1
2
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4
5
6
7
8
9
10

{# app/Resources/views/article/list.html.twig #}
{% extends 'layout.html.twig' %}
{% block body %}

Recent Articles


{% for article in articles %}
{{ include('article/article_details.html.twig', { 'article': article }) }}
{% endfor %}
{% endblock %}

The template is included using the {{ include() }} function. Notice that the template name follows
the same typical convention. The article_details.html.twig template uses an article variable,
which we pass to it. In this case, you could avoid doing this entirely, as all of the variables available
in list.html.twig are also available in article_details.html.twig (unless you set with_context5 to
false).
The {'article': article} syntax is the standard Twig syntax for hash maps (i.e. an array with
named keys). If you needed to pass in multiple elements, it would look like this: {'foo': foo,
'bar': bar}.

Embedding Controllers
In some cases, you need to do more than include a simple template. Suppose you have a sidebar in your
layout that contains the three most recent articles. Retrieving the three articles may include querying the
database or performing other heavy logic that can't be done from within a template.
The solution is to simply embed the result of an entire controller from your template. First, create a
controller that renders a certain number of recent articles:
Listing 7-12

1
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4
5
6
7
8
9
10
11
12
13
14
15

// src/AppBundle/Controller/ArticleController.php
namespace AppBundle\Controller;
// ...
class ArticleController extends Controller
{
public function recentArticlesAction($max = 3)
{
// make a database call or other logic
// to get the "$max" most recent articles
$articles = ...;
return $this->render(
'article/recent_list.html.twig',

5. http://twig.sensiolabs.org/doc/functions/include.html

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16
17
18
19 }

array('articles' => $articles)
);
}

The recent_list template is perfectly straightforward:
Listing 7-13

1 {# app/Resources/views/article/recent_list.html.twig #}
2 {% for article in articles %}
3

4
{{ article.title }}
5

6 {% endfor %}

Notice that the article URL is hardcoded in this example (e.g. /article/*slug*). This is a bad
practice. In the next section, you'll learn how to do this correctly.

To include the controller, you'll need to refer to it using the standard string syntax for controllers (i.e.
bundle:controller:action):
Listing 7-14

1
2
3
4
5
6
7
8
9

{# app/Resources/views/base.html.twig #}
{# ... #}


Whenever you find that you need a variable or a piece of information that you don't have access to
in a template, consider rendering a controller. Controllers are fast to execute and promote good code
organization and reuse. Of course, like all controllers, they should ideally be "skinny", meaning that as
much code as possible lives in reusable services.

Asynchronous Content with hinclude.js
Controllers can be embedded asynchronously using the hinclude.js6 JavaScript library. As the embedded
content comes from another page (or controller for that matter), Symfony uses a version of the standard
render function to configure hinclude tags:
Listing 7-15

1 {{ render_hinclude(controller('...')) }}
2 {{ render_hinclude(url('...')) }}

hinclude.js7 needs to be included in your page to work.

6. http://mnot.github.io/hinclude/
7. http://mnot.github.io/hinclude/

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When using a controller instead of a URL, you must enable the Symfony fragments configuration:
Listing 7-16

1 # app/config/config.yml
2 framework:
3
# ...
4
fragments: { path: /_fragment }

Default content (while loading or if JavaScript is disabled) can be set globally in your application
configuration:
Listing 7-17

1 # app/config/config.yml
2 framework:
3
# ...
4
templating:
5
hinclude_default_template: hinclude.html.twig

You can define default templates per render function (which will override any global default template
that is defined):
Listing 7-18

1 {{ render_hinclude(controller('...'), {
2
'default': 'default/content.html.twig'
3 }) }}

Or you can also specify a string to display as the default content:
Listing 7-19

1 {{ render_hinclude(controller('...'), {'default': 'Loading...'}) }}

Linking to Pages
Creating links to other pages in your application is one of the most common jobs for a template. Instead
of hardcoding URLs in templates, use the path Twig function (or the router helper in PHP) to generate
URLs based on the routing configuration. Later, if you want to modify the URL of a particular page, all
you'll need to do is change the routing configuration; the templates will automatically generate the new
URL.
First, link to the "_welcome" page, which is accessible via the following routing configuration:
Listing 7-20

1
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7
8
9
10
11
12
13
14
15

// src/AppBundle/Controller/WelcomeController.php
// ...
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
class WelcomeController extends Controller
{
/**
* @Route("/", name="_welcome")
*/
public function indexAction()
{
// ...
}
}

To link to the page, just use the path Twig function and refer to the route:
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Listing 7-21

1 Home

As expected, this will generate the URL /. Now, for a more complicated route:
Listing 7-22

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14
15

// src/AppBundle/Controller/ArticleController.php
// ...
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
class ArticleController extends Controller
{
/**
* @Route("/article/{slug}", name="article_show")
*/
public function showAction($slug)
{
// ...
}
}

In this case, you need to specify both the route name (article_show) and a value for the {slug}
parameter. Using this route, revisit the recent_list template from the previous section and link to the
articles correctly:
Listing 7-23

1 {# app/Resources/views/article/recent_list.html.twig #}
2 {% for article in articles %}
3

4
{{ article.title }}
5

6 {% endfor %}

You can also generate an absolute URL by using the url function:
Listing 7-24

1 Home

Linking to Assets
Templates also commonly refer to images, JavaScript, stylesheets and other assets. Of course you could
hard-code the path to these assets (e.g. /images/logo.png), but Symfony provides a more dynamic
option via the asset Twig function:
Listing 7-25

1 Symfony!
2
3

The asset function's main purpose is to make your application more portable. If your application lives at
the root of your host (e.g. http://example.com), then the rendered paths should be /images/logo.png.
But if your application lives in a subdirectory (e.g. http://example.com/my_app), each asset path should
render with the subdirectory (e.g. /my_app/images/logo.png). The asset function takes care of this by
determining how your application is being used and generating the correct paths accordingly.
Additionally, if you use the asset function, Symfony can automatically append a query string to your
asset, in order to guarantee that updated static assets won't be loaded from cache after being deployed.
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For example, /images/logo.png might look like /images/logo.png?v2. For more information, see the
version configuration option.
If you need to set a version for a specific asset, you can set the version argument if you are using Twig
(or the fourth argument if you are using PHP) to the desired version:
Listing 7-26

1 Symfony!

If you don't give a version or pass null, the default package version (from version) will be used. If you
pass false, versioned URL will be deactivated for this asset.
If you need absolute URLs for assets, you can use the absolute_url function if you are using Twig (or
the third argument if you are using PHP) to true:
Listing 7-27

1 Symfony!

Including Stylesheets and JavaScripts in Twig
No site would be complete without including JavaScript files and stylesheets. In Symfony, the inclusion
of these assets is handled elegantly by taking advantage of Symfony's template inheritance.
This section will teach you the philosophy behind including stylesheet and JavaScript assets in
Symfony. Symfony is also compatible with another library, called Assetic, which follows this
philosophy but allows you to do much more interesting things with those assets. For more
information on using Assetic see How to Use Assetic for Asset Management.

Start by adding two blocks to your base template that will hold your assets: one called stylesheets
inside the head tag and another called javascripts just above the closing body tag. These blocks will
contain all of the stylesheets and JavaScripts that you'll need throughout your site:
Listing 7-28

1 {# app/Resources/views/base.html.twig #}
2
3

4
{# ... #}
5
6
{% block stylesheets %}
7

8
{% endblock %}
9

10

11
{# ... #}
12
13
{% block javascripts %}
14

15
{% endblock %}
16

17

That's easy enough! But what if you need to include an extra stylesheet or JavaScript from a child
template? For example, suppose you have a contact page and you need to include a contact.css
stylesheet just on that page. From inside that contact page's template, do the following:
Listing 7-29

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1
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{# app/Resources/views/contact/contact.html.twig #}
{% extends 'base.html.twig' %}
{% block stylesheets %}
{{ parent() }}

{% endblock %}

{# ... #}

In the child template, you simply override the stylesheets block and put your new stylesheet tag inside
of that block. Of course, since you want to add to the parent block's content (and not actually replace
it), you should use the parent() Twig function to include everything from the stylesheets block of the
base template.
You can also include assets located in your bundles' Resources/public folder. You will need to run the
php bin/console assets:install target [--symlink] command, which moves (or symlinks) files
into the correct location. (target is by default "web").
Listing 7-30

1

The end result is a page that includes both the main.css and contact.css stylesheets.

Global Template Variables
During each request, Symfony will set a global template variable app in both Twig and PHP template
engines by default. The app variable is a GlobalVariables8 instance which will give you access to some
application specific variables automatically:
app.user
The current user object.
app.request
The request object.
app.session
The session object.
app.environment
The current environment (dev, prod, etc).
app.debug
True if in debug mode. False otherwise.
Listing 7-31

1

Username: {{ app.user.username }}


2 {% if app.debug %}
3

Request method: {{ app.request.method }}


4

Application Environment: {{ app.environment }}


5 {% endif %}

8. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Templating/GlobalVariables.html

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You can add your own global template variables. See the cookbook example on Global Variables.

Configuring and Using the templating Service
The heart of the template system in Symfony is the templating Engine. This special object is responsible
for rendering templates and returning their content. When you render a template in a controller, for
example, you're actually using the templating engine service. For example:
Listing 7-32

1 return $this->render('article/index.html.twig');

is equivalent to:
Listing 7-33

1
2
3
4
5
6

use Symfony\Component\HttpFoundation\Response;
$engine = $this->container->get('templating');
$content = $engine->render('article/index.html.twig');
return $response = new Response($content);

The templating engine (or "service") is preconfigured to work automatically inside Symfony. It can, of
course, be configured further in the application configuration file:
Listing 7-34

1 # app/config/config.yml
2 framework:
3
# ...
4
templating: { engines: ['twig'] }

Several configuration options are available and are covered in the Configuration Appendix.
The twig engine is mandatory to use the webprofiler (as well as many third-party bundles).

Overriding Bundle Templates
The Symfony community prides itself on creating and maintaining high quality bundles (see
KnpBundles.com9) for a large number of different features. Once you use a third-party bundle, you'll likely
need to override and customize one or more of its templates.
Suppose you've installed the imaginary open-source AcmeBlogBundle in your project. And while you're
really happy with everything, you want to override the blog "list" page to customize the markup
specifically for your application. By digging into the Blog controller of the AcmeBlogBundle, you find the
following:
Listing 7-35

1 public function indexAction()
2 {

9. http://knpbundles.com

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3
4
5
6
7
8
9
10 }

// some logic to retrieve the blogs
$blogs = ...;
$this->render(
'AcmeBlogBundle:Blog:index.html.twig',
array('blogs' => $blogs)
);

When the AcmeBlogBundle:Blog:index.html.twig is rendered, Symfony actually looks in two different
locations for the template:
1. app/Resources/AcmeBlogBundle/views/Blog/index.html.twig
2. src/Acme/BlogBundle/Resources/views/Blog/index.html.twig
To override the bundle template, just copy the index.html.twig template from the bundle to app/
Resources/AcmeBlogBundle/views/Blog/index.html.twig (the app/Resources/AcmeBlogBundle
directory won't exist, so you'll need to create it). You're now free to customize the template.
If you add a template in a new location, you may need to clear your cache (php bin/console
cache:clear), even if you are in debug mode.

This logic also applies to base bundle templates. Suppose also that each template in AcmeBlogBundle
inherits from a base template called AcmeBlogBundle::layout.html.twig. Just as before, Symfony will
look in the following two places for the template:
1. app/Resources/AcmeBlogBundle/views/layout.html.twig
2. src/Acme/BlogBundle/Resources/views/layout.html.twig
Once again, to override the template, just copy it from the bundle to app/Resources/AcmeBlogBundle/
views/layout.html.twig. You're now free to customize this copy as you see fit.
If you take a step back, you'll see that Symfony always starts by looking in the app/Resources/
{BUNDLE_NAME}/views/ directory for a template. If the template doesn't exist there, it continues by
checking inside the Resources/views directory of the bundle itself. This means that all bundle templates
can be overridden by placing them in the correct app/Resources subdirectory.
You can also override templates from within a bundle by using bundle inheritance. For more
information, see How to Use Bundle Inheritance to Override Parts of a Bundle.

Overriding Core Templates
Since the Symfony Framework itself is just a bundle, core templates can be overridden in the same way.
For example, the core TwigBundle contains a number of different "exception" and "error" templates that
can be overridden by copying each from the Resources/views/Exception directory of the TwigBundle
to, you guessed it, the app/Resources/TwigBundle/views/Exception directory.

Three-level Inheritance
One common way to use inheritance is to use a three-level approach. This method works perfectly with
the three different types of templates that were just covered:

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• Create an app/Resources/views/base.html.twig file that contains the main layout for your
application (like in the previous example). Internally, this template is called base.html.twig;
• Create a template for each "section" of your site. For example, the blog functionality would
have a template called blog/layout.html.twig that contains only blog section-specific
elements;
Listing 7-36

1
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3
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5
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7
8

{# app/Resources/views/blog/layout.html.twig #}
{% extends 'base.html.twig' %}
{% block body %}

Blog Application


{% block content %}{% endblock %}
{% endblock %}

• Create individual templates for each page and make each extend the appropriate section
template. For example, the "index" page would be called something close to blog/
index.html.twig and list the actual blog posts.
Listing 7-37

1
2
3
4
5
6
7
8
9

{# app/Resources/views/blog/index.html.twig #}
{% extends 'blog/layout.html.twig' %}
{% block content %}
{% for entry in blog_entries %}

{{ entry.title }}


{{ entry.body }}


{% endfor %}
{% endblock %}

Notice that this template extends the section template (blog/layout.html.twig) which in turn extends
the base application layout (base.html.twig). This is the common three-level inheritance model.
When building your application, you may choose to follow this method or simply make each page
template extend the base application template directly (e.g. {% extends 'base.html.twig' %}). The
three-template model is a best-practice method used by vendor bundles so that the base template for a
bundle can be easily overridden to properly extend your application's base layout.

Output Escaping
When generating HTML from a template, there is always a risk that a template variable may output
unintended HTML or dangerous client-side code. The result is that dynamic content could break the
HTML of the resulting page or allow a malicious user to perform a Cross Site Scripting10 (XSS) attack.
Consider this classic example:
Listing 7-38

1 Hello {{ name }}

Imagine the user enters the following code for their name:
Listing 7-39

1

Without any output escaping, the resulting template will cause a JavaScript alert box to pop up:

10. https://en.wikipedia.org/wiki/Cross-site_scripting

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Listing 7-40

1 Hello

And while this seems harmless, if a user can get this far, that same user should also be able to write
JavaScript that performs malicious actions inside the secure area of an unknowing, legitimate user.
The answer to the problem is output escaping. With output escaping on, the same template will render
harmlessly, and literally print the script tag to the screen:
Listing 7-41

1 Hello <script>alert('hello!')</script>

The Twig and PHP templating systems approach the problem in different ways. If you're using Twig,
output escaping is on by default and you're protected. In PHP, output escaping is not automatic, meaning
you'll need to manually escape where necessary.

Output Escaping in Twig
If you're using Twig templates, then output escaping is on by default. This means that you're protected
out-of-the-box from the unintentional consequences of user-submitted code. By default, the output
escaping assumes that content is being escaped for HTML output.
In some cases, you'll need to disable output escaping when you're rendering a variable that is trusted and
contains markup that should not be escaped. Suppose that administrative users are able to write articles
that contain HTML code. By default, Twig will escape the article body.
To render it normally, add the raw filter:
Listing 7-42

1 {{ article.body|raw }}

You can also disable output escaping inside a {% block %} area or for an entire template. For more
information, see Output Escaping11 in the Twig documentation.

Output Escaping in PHP
Output escaping is not automatic when using PHP templates. This means that unless you explicitly
choose to escape a variable, you're not protected. To use output escaping, use the special escape() view
method:
Listing 7-43

1 Hello escape($name) ?>

By default, the escape() method assumes that the variable is being rendered within an HTML context
(and thus the variable is escaped to be safe for HTML). The second argument lets you change the context.
For example, to output something in a JavaScript string, use the js context:
Listing 7-44

1 var myMsg = 'Hello escape($name, 'js') ?>';

Debugging
When using PHP, you can use the dump() function from the VarDumper component if you need to
quickly find the value of a variable passed. This is useful, for example, inside your controller:
Listing 7-45

11. http://twig.sensiolabs.org/doc/api.html#escaper-extension

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// src/AppBundle/Controller/ArticleController.php
namespace AppBundle\Controller;
// ...
class ArticleController extends Controller
{
public function recentListAction()
{
$articles = ...;
dump($articles);

// ...
}
}

The output of the dump() function is then rendered in the web developer toolbar.

The same mechanism can be used in Twig templates thanks to dump function:
Listing 7-46

1
2
3
4
5
6
7
8

{# app/Resources/views/article/recent_list.html.twig #}
{{ dump(articles) }}
{% for article in articles %}

{{ article.title }}

{% endfor %}

The variables will only be dumped if Twig's debug setting (in config.yml) is true. By default this means
that the variables will be dumped in the dev environment but not the prod environment.

Syntax Checking
You can check for syntax errors in Twig templates using the lint:twig console command:
Listing 7-47

1
2
3
4
5

# You can check by filename:
$ php bin/console lint:twig app/Resources/views/article/recent_list.html.twig
# or by directory:
$ php bin/console lint:twig app/Resources/views

Template Formats
Templates are a generic way to render content in any format. And while in most cases you'll use templates
to render HTML content, a template can just as easily generate JavaScript, CSS, XML or any other format
you can dream of.
For example, the same "resource" is often rendered in several formats. To render an article index page in
XML, simply include the format in the template name:
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• XML template name: article/index.xml.twig
• XML template filename: index.xml.twig
In reality, this is nothing more than a naming convention and the template isn't actually rendered
differently based on its format.
In many cases, you may want to allow a single controller to render multiple different formats based on
the "request format". For that reason, a common pattern is to do the following:
Listing 7-48

1 public function indexAction(Request $request)
2 {
3
$format = $request->getRequestFormat();
4
5
return $this->render('article/index.'.$format.'.twig');
6 }

The getRequestFormat on the Request object defaults to html, but can return any other format based
on the format requested by the user. The request format is most often managed by the routing, where a
route can be configured so that /contact sets the request format to html while /contact.xml sets the
format to xml. For more information, see the Advanced Example in the Routing chapter.
To create links that include the format parameter, include a _format key in the parameter hash:
Listing 7-49

1
2
PDF Version
3


Final Thoughts
The templating engine in Symfony is a powerful tool that can be used each time you need to generate
presentational content in HTML, XML or any other format. And though templates are a common way to
generate content in a controller, their use is not mandatory. The Response object returned by a controller
can be created with or without the use of a template:
Listing 7-50

1
2
3
4
5

// creates a Response object whose content is the rendered template
$response = $this->render('article/index.html.twig');
// creates a Response object whose content is simple text
$response = new Response('response content');

Symfony's templating engine is very flexible and two different template renderers are available by default:
the traditional PHP templates and the sleek and powerful Twig templates. Both support a template
hierarchy and come packaged with a rich set of helper functions capable of performing the most common
tasks.
Overall, the topic of templating should be thought of as a powerful tool that's at your disposal. In some
cases, you may not need to render a template, and in Symfony, that's absolutely fine.

Learn more from the Cookbook
• How to Use PHP instead of Twig for Templates
• How to Customize Error Pages
• How to Write a custom Twig Extension

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Chapter 8

Configuring Symfony (and Environments)
An application consists of a collection of bundles representing all the features and capabilities of your
application. Each bundle can be customized via configuration files written in YAML, XML or PHP. By
default, the main configuration file lives in the app/config/ directory and is called either config.yml,
config.xml or config.php depending on which format you prefer:
Listing 8-1

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

# app/config/config.yml
imports:
- { resource: parameters.yml }
- { resource: security.yml }
framework:
secret:
router:
# ...

'%secret%'
{ resource: '%kernel.root_dir%/config/routing.yml' }

# Twig Configuration
twig:
debug:
'%kernel.debug%'
strict_variables: '%kernel.debug%'
# ...

You'll learn exactly how to load each file/format in the next section Environments.

Each top-level entry like framework or twig defines the configuration for a particular bundle. For
example, the framework key defines the configuration for the core Symfony FrameworkBundle and
includes configuration for the routing, templating, and other core systems.
For now, don't worry about the specific configuration options in each section. The configuration file
ships with sensible defaults. As you read more and explore each part of Symfony, you'll learn about the
specific configuration options of each feature.

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Configuration Formats
Throughout the chapters, all configuration examples will be shown in all three formats (YAML,
XML and PHP). Each has its own advantages and disadvantages. The choice of which to use is up
to you:
• YAML: Simple, clean and readable (learn more about YAML in "The YAML Format");
• XML: More powerful than YAML at times and supports IDE autocompletion;
• PHP: Very powerful but less readable than standard configuration formats.

Default Configuration Dump
You can dump the default configuration for a bundle in YAML to the console using the config:dumpreference command. Here is an example of dumping the default FrameworkBundle configuration:
Listing 8-2

1 $ php bin/console config:dump-reference FrameworkBundle

The extension alias (configuration key) can also be used:
Listing 8-3

1 $ php bin/console config:dump-reference framework

See the cookbook article: How to Load Service Configuration inside a Bundle for information on
adding configuration for your own bundle.

Environments
An application can run in various environments. The different environments share the same PHP code
(apart from the front controller), but use different configuration. For instance, a dev environment will
log warnings and errors, while a prod environment will only log errors. Some files are rebuilt on each
request in the dev environment (for the developer's convenience), but cached in the prod environment.
All environments live together on the same machine and execute the same application.
A Symfony project generally begins with three environments (dev, test and prod), though creating new
environments is easy. You can view your application in different environments simply by changing the
front controller in your browser. To see the application in the dev environment, access the application
via the development front controller:
Listing 8-4

1 http://localhost/app_dev.php/random/10

If you'd like to see how your application will behave in the production environment, call the prod front
controller instead:
Listing 8-5

1 http://localhost/app.php/random/10

Since the prod environment is optimized for speed; the configuration, routing and Twig templates are
compiled into flat PHP classes and cached. When viewing changes in the prod environment, you'll need
to clear these cached files and allow them to rebuild:
Listing 8-6

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1 $ php bin/console cache:clear --env=prod --no-debug

If you open the web/app.php file, you'll find that it's configured explicitly to use the prod
environment:
Listing 8-7

1 $kernel = new AppKernel('prod', false);

You can create a new front controller for a new environment by copying this file and changing prod
to some other value.

The test environment is used when running automated tests and cannot be accessed directly
through the browser. See the testing chapter for more details.

When using the server:run command to start a server, http://localhost:8000/ will use the dev
front controller of your application.

Environment Configuration
The AppKernel class is responsible for actually loading the configuration file of your choice:
Listing 8-8

1
2
3
4
5
6
7

// app/AppKernel.php
public function registerContainerConfiguration(LoaderInterface $loader)
{
$loader->load(
__DIR__.'/config/config_'.$this->getEnvironment().'.yml'
);
}

You already know that the .yml extension can be changed to .xml or .php if you prefer to use either
XML or PHP to write your configuration. Notice also that each environment loads its own configuration
file. Consider the configuration file for the dev environment.
Listing 8-9

1
2
3
4
5
6
7
8
9

# app/config/config_dev.yml
imports:
- { resource: config.yml }
framework:
router:
{ resource: '%kernel.root_dir%/config/routing_dev.yml' }
profiler: { only_exceptions: false }

# ...

The imports key is similar to a PHP include statement and guarantees that the main configuration file
(config.yml) is loaded first. The rest of the file tweaks the default configuration for increased logging
and other settings conducive to a development environment.
Both the prod and test environments follow the same model: each environment imports the base
configuration file and then modifies its configuration values to fit the needs of the specific environment.
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This is just a convention, but one that allows you to reuse most of your configuration and customize just
pieces of it between environments.

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Chapter 9

The Bundle System
A bundle is similar to a plugin in other software, but even better. The key difference is that everything
is a bundle in Symfony, including both the core framework functionality and the code written for your
application. Bundles are first-class citizens in Symfony. This gives you the flexibility to use pre-built
features packaged in third-party bundles or to distribute your own bundles. It makes it easy to pick and
choose which features to enable in your application and to optimize them the way you want.
While you'll learn the basics here, an entire cookbook entry is devoted to the organization and best
practices of bundles.

A bundle is simply a structured set of files within a directory that implement a single feature. You might
create a BlogBundle, a ForumBundle or a bundle for user management (many of these exist already as
open source bundles). Each directory contains everything related to that feature, including PHP files,
templates, stylesheets, JavaScript files, tests and anything else. Every aspect of a feature exists in a bundle
and every feature lives in a bundle.
Bundles used in your applications must be enabled by registering them in the registerBundles()
method of the AppKernel class:
Listing 9-1

1 // app/AppKernel.php
2 public function registerBundles()
3 {
4
$bundles = array(
5
new Symfony\Bundle\FrameworkBundle\FrameworkBundle(),
6
new Symfony\Bundle\SecurityBundle\SecurityBundle(),
7
new Symfony\Bundle\TwigBundle\TwigBundle(),
8
new Symfony\Bundle\MonologBundle\MonologBundle(),
9
new Symfony\Bundle\SwiftmailerBundle\SwiftmailerBundle(),
10
new Symfony\Bundle\DoctrineBundle\DoctrineBundle(),
11
new Symfony\Bundle\AsseticBundle\AsseticBundle(),
12
new Sensio\Bundle\FrameworkExtraBundle\SensioFrameworkExtraBundle(),
13
new AppBundle\AppBundle(),
14
);
15

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16
17
18
19
20
21
22
23 }

if (in_array($this->getEnvironment(), array('dev', 'test'))) {
$bundles[] = new Symfony\Bundle\WebProfilerBundle\WebProfilerBundle();
$bundles[] = new Sensio\Bundle\DistributionBundle\SensioDistributionBundle();
$bundles[] = new Sensio\Bundle\GeneratorBundle\SensioGeneratorBundle();
}
return $bundles;

With the registerBundles() method, you have total control over which bundles are used by your
application (including the core Symfony bundles).
A bundle can live anywhere as long as it can be autoloaded (via the autoloader configured at app/
autoload.php).

Creating a Bundle
The Symfony Standard Edition comes with a handy task that creates a fully-functional bundle for you.
Of course, creating a bundle by hand is pretty easy as well.
To show you how simple the bundle system is, create a new bundle called AcmeTestBundle and enable
it.
The Acme portion is just a dummy name that should be replaced by some "vendor" name that
represents you or your organization (e.g. ABCTestBundle for some company named ABC).

Start by creating a src/Acme/TestBundle/ directory and adding a new file called AcmeTestBundle.php:
Listing 9-2

1
2
3
4
5
6
7
8

// src/Acme/TestBundle/AcmeTestBundle.php
namespace Acme\TestBundle;
use Symfony\Component\HttpKernel\Bundle\Bundle;
class AcmeTestBundle extends Bundle
{
}

The name AcmeTestBundle follows the standard Bundle naming conventions. You could also
choose to shorten the name of the bundle to simply TestBundle by naming this class TestBundle
(and naming the file TestBundle.php).

This empty class is the only piece you need to create the new bundle. Though commonly empty, this
class is powerful and can be used to customize the behavior of the bundle.
Now that you've created the bundle, enable it via the AppKernel class:
Listing 9-3

1 // app/AppKernel.php
2 public function registerBundles()
3 {

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4
5
6
7
8
9
10
11
12
13 }

$bundles = array(
// ...

// register your bundle
new Acme\TestBundle\AcmeTestBundle(),
);
// ...
return $bundles;

And while it doesn't do anything yet, AcmeTestBundle is now ready to be used.
And as easy as this is, Symfony also provides a command-line interface for generating a basic bundle
skeleton:
Listing 9-4

1 $ php bin/console generate:bundle --namespace=Acme/TestBundle

The bundle skeleton generates a basic controller, template and routing resource that can be customized.
You'll learn more about Symfony's command-line tools later.
Whenever creating a new bundle or using a third-party bundle, always make sure the bundle has
been enabled in registerBundles(). When using the generate:bundle command, this is done
for you.

Bundle Directory Structure
The directory structure of a bundle is simple and flexible. By default, the bundle system follows a
set of conventions that help to keep code consistent between all Symfony bundles. Take a look at
AcmeDemoBundle, as it contains some of the most common elements of a bundle:
Controller/
Contains the controllers of the bundle (e.g. RandomController.php).
DependencyInjection/
Holds certain Dependency Injection Extension classes, which may import service configuration,
register compiler passes or more (this directory is not necessary).
Resources/config/
Houses configuration, including routing configuration (e.g. routing.yml).
Resources/views/
Holds templates organized by controller name (e.g. Hello/index.html.twig).
Resources/public/
Contains web assets (images, stylesheets, etc) and is copied or symbolically linked into the project
web/ directory via the assets:install console command.
Tests/
Holds all tests for the bundle.
A bundle can be as small or large as the feature it implements. It contains only the files you need and
nothing else.

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As you move through the book, you'll learn how to persist objects to a database, create and validate
forms, create translations for your application, write tests and much more. Each of these has their own
place and role within the bundle.
third-party bundles: http://knpbundles.com1

1. http://knpbundles.com

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Chapter 10

Databases and Doctrine
One of the most common and challenging tasks for any application involves persisting and reading
information to and from a database. Although the Symfony full-stack Framework doesn't integrate any
ORM by default, the Symfony Standard Edition, which is the most widely used distribution, comes
integrated with Doctrine1, a library whose sole goal is to give you powerful tools to make this easy. In this
chapter, you'll learn the basic philosophy behind Doctrine and see how easy working with a database can
be.
Doctrine is totally decoupled from Symfony and using it is optional. This chapter is all about
the Doctrine ORM, which aims to let you map objects to a relational database (such as MySQL,
PostgreSQL or Microsoft SQL). If you prefer to use raw database queries, this is easy, and explained
in the "How to Use Doctrine DBAL" cookbook entry.
You can also persist data to MongoDB2 using Doctrine ODM library. For more information, read
the "DoctrineMongoDBBundle3" documentation.

A Simple Example: A Product
The easiest way to understand how Doctrine works is to see it in action. In this section, you'll configure
your database, create a Product object, persist it to the database and fetch it back out.

Configuring the Database
Before you really begin, you'll need to configure your database connection information. By convention,
this information is usually configured in an app/config/parameters.yml file:
Listing 10-1

1 # app/config/parameters.yml
2 parameters:
3
database_driver:
pdo_mysql

1. http://www.doctrine-project.org/
2. https://www.mongodb.org/
3. https://symfony.com/doc/current/bundles/DoctrineMongoDBBundle/index.html

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4
database_host:
5
database_name:
6
database_user:
7
database_password:
8
9 # ...

localhost
test_project
root
password

Defining the configuration via parameters.yml is just a convention. The parameters defined in
that file are referenced by the main configuration file when setting up Doctrine:
Listing 10-2

1 # app/config/config.yml
2 doctrine:
3
dbal:
4
driver:
'%database_driver%'
5
host:
'%database_host%'
6
dbname:
'%database_name%'
7
user:
'%database_user%'
8
password: '%database_password%'

By separating the database information into a separate file, you can easily keep different versions
of the file on each server. You can also easily store database configuration (or any sensitive
information) outside of your project, like inside your Apache configuration, for example. For more
information, see How to Set external Parameters in the Service Container.

Now that Doctrine can connect to your database, the following command can automatically generate an
empty test_project database for you:
Listing 10-3

1 $ php bin/console doctrine:database:create

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Setting up the Database to be UTF8
One mistake even seasoned developers make when starting a Symfony project is forgetting to set
up default charset and collation on their database, ending up with latin type collations, which are
default for most databases. They might even remember to do it the very first time, but forget that
it's all gone after running a relatively common command during development:
Listing 10-4

1 $ php bin/console doctrine:database:drop --force
2 $ php bin/console doctrine:database:create

Setting UTF8 defaults for MySQL is as simple as adding a few lines to your configuration file
(typically my.cnf):
Listing 10-5

1
2
3
4

[mysqld]
# Version 5.5.3 introduced "utf8mb4", which is recommended
collation-server
= utf8mb4_general_ci # Replaces utf8_general_ci
character-set-server = utf8mb4
# Replaces utf8

You can also change the defaults for Doctrine so that the generated SQL uses the correct character
set.
Listing 10-6

1 # app/config/config.yml
2 doctrine:
3
dbal:
4
charset: utf8mb4
5
default_table_options:
6
charset: utf8mb4
7
collate: utf8mb4_unicode_ci

We recommend against MySQL's utf8 character set, since it does not support 4-byte unicode
characters, and strings containing them will be truncated. This is fixed by the newer utf8mb4
character set4.

If you want to use SQLite as your database, you need to set the path where your database file
should be stored:
Listing 10-7

1 # app/config/config.yml
2 doctrine:
3
dbal:
4
driver: pdo_sqlite
5
path: '%kernel.root_dir%/sqlite.db'
6
charset: UTF8

Creating an Entity Class
Suppose you're building an application where products need to be displayed. Without even thinking
about Doctrine or databases, you already know that you need a Product object to represent those
products. Create this class inside the Entity directory of your AppBundle:
Listing 10-8

1 // src/AppBundle/Entity/Product.php
2 namespace AppBundle\Entity;

4. https://dev.mysql.com/doc/refman/5.5/en/charset-unicode-utf8mb4.html

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3
4 class Product
5 {
6
private $name;
7
private $price;
8
private $description;
9 }

The class - often called an "entity", meaning a basic class that holds data - is simple and helps fulfill the
business requirement of needing products in your application. This class can't be persisted to a database
yet - it's just a simple PHP class.
Once you learn the concepts behind Doctrine, you can have Doctrine create simple entity classes
for you. This will ask you interactive questions to help you build any entity:
Listing 10-9

1 $ php bin/console doctrine:generate:entity

Add Mapping Information
Doctrine allows you to work with databases in a much more interesting way than just fetching rows of
scalar data into an array. Instead, Doctrine allows you to fetch entire objects out of the database, and to
persist entire objects to the database. For Doctrine to be able to do this, you must map your database
tables to specific PHP classes, and the columns on those tables must be mapped to specific properties on
their corresponding PHP classes.

You'll provide this mapping information in the form of "metadata", a collection of rules that tells Doctrine
exactly how the Product class and its properties should be mapped to a specific database table. This
metadata can be specified in a number of different formats, including YAML, XML or directly inside the
Product class via DocBlock annotations:
Listing 10-10

1
2
3
4
5
6
7
8
9
10
11

// src/AppBundle/Entity/Product.php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;

/**
* @ORM\Entity
* @ORM\Table(name="product")
*/
class Product
{

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12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33 }

/**
* @ORM\Column(type="integer")
* @ORM\Id
* @ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* @ORM\Column(type="string", length=100)
*/
private $name;
/**
* @ORM\Column(type="decimal", scale=2)
*/
private $price;
/**
* @ORM\Column(type="text")
*/
private $description;

A bundle can accept only one metadata definition format. For example, it's not possible to mix
YAML metadata definitions with annotated PHP entity class definitions.

The table name is optional and if omitted, will be determined automatically based on the name of
the entity class.

Doctrine allows you to choose from a wide variety of different field types, each with their own options.
For information on the available field types, see the Doctrine Field Types Reference section.
You can also check out Doctrine's Basic Mapping Documentation5 for all details about mapping information.
If you use annotations, you'll need to prepend all annotations with ORM\ (e.g. ORM\Column(...)), which is not
shown in Doctrine's documentation. You'll also need to include the use Doctrine\ORM\Mapping as ORM;
statement, which imports the ORM annotations prefix.

Be careful if the names of your entity classes (or their properties) are also reserved SQL keywords
like GROUP or USER. For example, if your entity's class name is Group, then, by default, the
corresponding table name would be group. This will cause an SQL error in some database engines.
See Doctrine's Reserved SQL keywords documentation6 for details on how to properly escape these
names. Alternatively, if you're free to choose your database schema, simply map to a different table
name or column name. See Doctrine's Creating Classes for the Database7 and Property Mapping8
documentation.

5.
6.
7.
8.

http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/basic-mapping.html
http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/basic-mapping.html#quoting-reserved-words
http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/basic-mapping.html#creating-classes-for-the-database
http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/basic-mapping.html#property-mapping

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When using another library or program (e.g. Doxygen) that uses annotations, you should place
the @IgnoreAnnotation annotation on the class to indicate which annotations Symfony should
ignore.
For example, to prevent the @fn annotation from throwing an exception, add the following:
Listing 10-11

1 /**
2 * @IgnoreAnnotation("fn")
3 */
4 class Product
5 // ...

Generating Getters and Setters
Even though Doctrine now knows how to persist a Product object to the database, the class itself isn't
really useful yet. Since Product is just a regular PHP class with private properties, you need to create
public getter and setter methods (e.g. getName(), setName($name)) in order to access its properties in
the rest of your application's code. Fortunately, the following command can generate these boilerplate
methods automatically:
Listing 10-12

1 $ php bin/console doctrine:generate:entities AppBundle/Entity/Product

This command makes sure that all the getters and setters are generated for the Product class. This is a
safe command - you can run it over and over again: it only generates getters and setters that don't exist
(i.e. it doesn't replace your existing methods).
Keep in mind that Doctrine's entity generator produces simple getters/setters. You should review
the generated methods and add any logic, if necessary, to suit the needs of your application.

More about doctrine:generate:entities
With the doctrine:generate:entities command you can:
• generate getter and setter methods in entity classes;
• generate repository classes on behalf of entities configured
@ORM\Entity(repositoryClass="...") annotation;
• generate the appropriate constructor for 1:n and n:m relations.

with

the

The doctrine:generate:entities command saves a backup of the original Product.php named
Product.php~. In some cases, the presence of this file can cause a "Cannot redeclare class" error.
It can be safely removed. You can also use the --no-backup option to prevent generating these
backup files.
Note that you don't need to use this command. You could also write the necessary getters and
setters by hand. This option simply exists to save you time, since creating these methods is often a
common task during development.

You can also generate all known entities (i.e. any PHP class with Doctrine mapping information) of a
bundle or an entire namespace:
Listing 10-13

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1
2
3
4
5

# generates all entities in the AppBundle
$ php bin/console doctrine:generate:entities AppBundle
# generates all entities of bundles in the Acme namespace
$ php bin/console doctrine:generate:entities Acme

Creating the Database Tables/Schema
You now have a usable Product class with mapping information so that Doctrine knows exactly how to
persist it. Of course, you don't yet have the corresponding product table in your database. Fortunately,
Doctrine can automatically create all the database tables needed for every known entity in your
application. To do this, run:
Listing 10-14

1 $ php bin/console doctrine:schema:update --force

Actually, this command is incredibly powerful. It compares what your database should look like
(based on the mapping information of your entities) with how it actually looks, and executes the
SQL statements needed to update the database schema to where it should be. In other words, if
you add a new property with mapping metadata to Product and run this task, it will execute the
"ALTER TABLE" statement needed to add that new column to the existing product table.
An even better way to take advantage of this functionality is via migrations9, which allow you to
generate these SQL statements and store them in migration classes that can be run systematically
on your production server in order to update and track changes to your database schema safely
and reliably.
Whether or not you take advantage of migrations, the doctrine:schema:update command should
only be used during development. It should not be used in a production environment.

Your database now has a fully-functional product table with columns that match the metadata you've
specified.

Persisting Objects to the Database
Now that you have mapped the Product entity to its corresponding product table, you're ready to persist
Product objects to the database. From inside a controller, this is pretty easy. Add the following method
to the DefaultController of the bundle:
Listing 10-15

1
2
3
4
5
6
7
8
9
10
11
12
13
14

// src/AppBundle/Controller/DefaultController.php
// ...
use AppBundle\Entity\Product;
use Symfony\Component\HttpFoundation\Response;
// ...
public function createAction()
{
$product = new Product();
$product->setName('Keyboard');
$product->setPrice(19.99);
$product->setDescription('Ergonomic and stylish!');

9. https://symfony.com/doc/current/bundles/DoctrineMigrationsBundle/index.html

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15
16
17
18
19
20
21
22
23
24 }

$em = $this->getDoctrine()->getManager();

// tells Doctrine you want to (eventually) save the Product (no queries yet)
$em->persist($product);
// actually executes the queries (i.e. the INSERT query)
$em->flush();
return new Response('Saved new product with id '.$product->getId());

If you're following along with this example, you'll need to create a route that points to this action
to see it work.

This article shows working with Doctrine from within a controller by using the getDoctrine()10
method of the controller. This method is a shortcut to get the doctrine service. You can work with
Doctrine anywhere else by injecting that service in the service. See Service Container for more on
creating your own services.

Take a look at the previous example in more detail:
• lines 10-13 In this section, you instantiate and work with the $product object like any other
normal PHP object.
• line 15 This line fetches Doctrine's entity manager object, which is responsible for the process
of persisting objects to, and fetching objects from, the database.
• line 17 The persist($product) call tells Doctrine to "manage" the $product object. This
does not cause a query to be made to the database.
• line 18 When the flush() method is called, Doctrine looks through all of the objects that it's
managing to see if they need to be persisted to the database. In this example, the $product
object's data doesn't exist in the database, so the entity manager executes an INSERT query,
creating a new row in the product table.
In fact, since Doctrine is aware of all your managed entities, when you call the flush() method,
it calculates an overall changeset and executes the queries in the correct order. It utilizes cached
prepared statement to slightly improve the performance. For example, if you persist a total of 100
Product objects and then subsequently call flush(), Doctrine will execute 100 INSERT queries
using a single prepared statement object.

Whether creating or updating objects, the workflow is always the same. In the next section, you'll see
how Doctrine is smart enough to automatically issue an UPDATE query if the entity already exists in the
database.
Doctrine provides a library that allows you to programmatically load testing data into your project
(i.e. "fixture data"). For information, see the "DoctrineFixturesBundle11" documentation.

10. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/Controller/Controller.html#method_getDoctrine
11. https://symfony.com/doc/current/bundles/DoctrineFixturesBundle/index.html

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Fetching Objects from the Database
Fetching an object back out of the database is even easier. For example, suppose you've configured a
route to display a specific Product based on its id value:
Listing 10-16

1 public function showAction($productId)
2 {
3
$product = $this->getDoctrine()
4
->getRepository('AppBundle:Product')
5
->find($productId);
6
7
if (!$product) {
8
throw $this->createNotFoundException(
9
'No product found for id '.$productId
10
);
11
}
12
13
// ... do something, like pass the $product object into a template
14 }

You can achieve the equivalent of this without writing any code by using the @ParamConverter
shortcut. See the FrameworkExtraBundle documentation12 for more details.

When you query for a particular type of object, you always use what's known as its "repository". You can
think of a repository as a PHP class whose only job is to help you fetch entities of a certain class. You can
access the repository object for an entity class via:
Listing 10-17

1 $repository = $this->getDoctrine()
2
->getRepository('AppBundle:Product');

The AppBundle:Product string is a shortcut you can use anywhere in Doctrine instead of the full
class name of the entity (i.e. AppBundle\Entity\Product). As long as your entity lives under the
Entity namespace of your bundle, this will work.

Once you have a repository object, you can access all sorts of helpful methods:
Listing 10-18

1
2
3
4
5
6
7
8
9
10
11
12

// query for a single product by its primary key (usually "id")
$product = $repository->find($productId);
// dynamic method names to find a single product based on a column value
$product = $repository->findOneById($productId);
$product = $repository->findOneByName('Keyboard');
// dynamic method names to find a group of products based on a column value
$products = $repository->findByPrice(19.99);
// find *all* products
$products = $repository->findAll();

12. https://symfony.com/doc/current/bundles/SensioFrameworkExtraBundle/annotations/converters.html

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Of course, you can also issue complex queries, which you'll learn more about in the Querying for
Objects section.

You can also take advantage of the useful findBy and findOneBy methods to easily fetch objects based
on multiple conditions:
Listing 10-19

1
2
3
4
5
6
7
8
9
10

// query for a single product matching the given name and price
$product = $repository->findOneBy(
array('name' => 'Keyboard', 'price' => 19.99)
);
// query for multiple products matching the given name, ordered by price
$products = $repository->findBy(
array('name' => 'Keyboard'),
array('price' => 'ASC')
);

When you render any page, you can see how many queries were made in the bottom right corner
of the web debug toolbar.

If you click the icon, the profiler will open, showing you the exact queries that were made.
The icon will turn yellow if there were more than 50 queries on the page. This could indicate that
something is not correct.

Updating an Object
Once you've fetched an object from Doctrine, updating it is easy. Suppose you have a route that maps a
product id to an update action in a controller:
Listing 10-20

1 public function updateAction($productId)
2 {
3
$em = $this->getDoctrine()->getManager();
4
$product = $em->getRepository('AppBundle:Product')->find($productId);
5
6
if (!$product) {
7
throw $this->createNotFoundException(

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8
9
10
11
12
13
14
15
16 }

'No product found for id '.$productId
);
}
$product->setName('New product name!');
$em->flush();
return $this->redirectToRoute('homepage');

Updating an object involves just three steps:
1. fetching the object from Doctrine;
2. modifying the object;
3. calling flush() on the entity manager
Notice that calling $em->persist($product) isn't necessary. Recall that this method simply tells
Doctrine to manage or "watch" the $product object. In this case, since you fetched the $product object
from Doctrine, it's already managed.

Deleting an Object
Deleting an object is very similar, but requires a call to the remove() method of the entity manager:
Listing 10-21

1 $em->remove($product);
2 $em->flush();

As you might expect, the remove() method notifies Doctrine that you'd like to remove the given object
from the database. The actual DELETE query, however, isn't actually executed until the flush() method
is called.

Querying for Objects
You've already seen how the repository object allows you to run basic queries without any work:
Listing 10-22

1 $product = $repository->find($productId);
2 $product = $repository->findOneByName('Keyboard');

Of course, Doctrine also allows you to write more complex queries using the Doctrine Query Language
(DQL). DQL is similar to SQL except that you should imagine that you're querying for one or more
objects of an entity class (e.g. Product) instead of querying for rows on a table (e.g. product).
When querying in Doctrine, you have two options: writing pure Doctrine queries or using Doctrine's
Query Builder.

Querying for Objects with DQL
Imagine that you want to query for products, but only return products that cost more than 19.99,
ordered from cheapest to most expensive. You can use Doctrine's native SQL-like language called DQL
to make a query for this:
Listing 10-23

1 $em = $this->getDoctrine()->getManager();
2 $query = $em->createQuery(
3
'SELECT p

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4
FROM AppBundle:Product p
5
WHERE p.price > :price
6
ORDER BY p.price ASC'
7 )->setParameter('price', '19.99');
8
9 $products = $query->getResult();

If you're comfortable with SQL, then DQL should feel very natural. The biggest difference is that you
need to think in terms of "objects" instead of rows in a database. For this reason, you select from the
AppBundle:Product object (an optional shortcut for AppBundle\Entity\Product) and then alias it as p.
Take note of the setParameter() method. When working with Doctrine, it's always a good idea
to set any external values as "placeholders" (:price in the example above) as it prevents SQL
injection attacks.

The getResult() method returns an array of results. To get only one result, you can use
getOneOrNullResult():
Listing 10-24

1 $product = $query->setMaxResults(1)->getOneOrNullResult();

The DQL syntax is incredibly powerful, allowing you to easily join between entities (the topic of relations
will be covered later), group, etc. For more information, see the official Doctrine Query Language13
documentation.

Querying for Objects Using Doctrine's Query Builder
Instead of writing a DQL string, you can use a helpful object called the QueryBuilder to build that string
for you. This is useful when the actual query depends on dynamic conditions, as your code soon becomes
hard to read with DQL as you start to concatenate strings:
Listing 10-25

1
2
3
4
5
6
7
8
9
10
11
12
13
14

$repository = $this->getDoctrine()
->getRepository('AppBundle:Product');

// createQueryBuilder automatically selects FROM AppBundle:Product
// and aliases it to "p"
$query = $repository->createQueryBuilder('p')
->where('p.price > :price')
->setParameter('price', '19.99')
->orderBy('p.price', 'ASC')
->getQuery();
$products = $query->getResult();
// to get just one result:
// $product = $query->setMaxResults(1)->getOneOrNullResult();

The QueryBuilder object contains every method necessary to build your query. By calling the
getQuery() method, the query builder returns a normal Query object, which can be used to get the result
of the query.
For more information on Doctrine's Query Builder, consult Doctrine's Query Builder14 documentation.

13. http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/dql-doctrine-query-language.html
14. http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/query-builder.html

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Custom Repository Classes
In the previous sections, you began constructing and using more complex queries from inside a
controller. In order to isolate, test and reuse these queries, it's a good practice to create a custom
repository class for your entity and add methods with your query logic there.
To do this, add the name of the repository class to your mapping definition:
Listing 10-26

1
2
3
4
5
6
7
8
9
10
11
12

// src/AppBundle/Entity/Product.php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;

/**
* @ORM\Entity(repositoryClass="AppBundle\Entity\ProductRepository")
*/
class Product
{
//...
}

Doctrine can generate the repository class for you by running the same command used earlier to generate
the missing getter and setter methods:
Listing 10-27

1 $ php bin/console doctrine:generate:entities AppBundle

Next, add a new method - findAllOrderedByName() - to the newly generated repository class. This
method will query for all the Product entities, ordered alphabetically.
Listing 10-28

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

// src/AppBundle/Entity/ProductRepository.php
namespace AppBundle\Entity;
use Doctrine\ORM\EntityRepository;
class ProductRepository extends EntityRepository
{
public function findAllOrderedByName()
{
return $this->getEntityManager()
->createQuery(
'SELECT p FROM AppBundle:Product p ORDER BY p.name ASC'
)
->getResult();
}
}

The entity manager can be accessed via $this->getEntityManager() from inside the repository.

You can use this new method just like the default finder methods of the repository:
Listing 10-29

1 $em = $this->getDoctrine()->getManager();
2 $products = $em->getRepository('AppBundle:Product')
3
->findAllOrderedByName();

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When using a custom repository class, you still have access to the default finder methods such as
find() and findAll().

Entity Relationships/Associations
Suppose that the products in your application all belong to exactly one "category". In this case, you'll
need a Category object and a way to relate a Product object to a Category object. Start by creating the
Category entity. Since you know that you'll eventually need to persist the class through Doctrine, you
can let Doctrine create the class for you.
Listing 10-30

1 $ php bin/console doctrine:generate:entity --no-interaction \
2
--entity="AppBundle:Category" \
3
--fields="name:string(255)"

This task generates the Category entity for you, with an id field, a name field and the associated getter
and setter functions.

Relationship Mapping Metadata
To relate the Category and Product entities, start by creating a products property on the Category class:
Listing 10-31

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

// src/AppBundle/Entity/Category.php
// ...
use Doctrine\Common\Collections\ArrayCollection;
class Category
{
// ...

/**
* @ORM\OneToMany(targetEntity="Product", mappedBy="category")
*/
private $products;
public function __construct()
{
$this->products = new ArrayCollection();
}
}

First, since a Category object will relate to many Product objects, a products array property is added
to hold those Product objects. Again, this isn't done because Doctrine needs it, but instead because it
makes sense in the application for each Category to hold an array of Product objects.
The code in the __construct() method is important because Doctrine requires the $products
property to be an ArrayCollection object. This object looks and acts almost exactly like an array,
but has some added flexibility. If this makes you uncomfortable, don't worry. Just imagine that it's
an array and you'll be in good shape.

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The targetEntity value in the decorator used above can reference any entity with a valid namespace,
not just entities defined in the same namespace. To relate to an entity defined in a different class or
bundle, enter a full namespace as the targetEntity.

Next, since each Product class can relate to exactly one Category object, you'll want to add a $category
property to the Product class:
Listing 10-32

1
2
3
4
5
6
7
8
9
10
11
12
13

// src/AppBundle/Entity/Product.php
// ...
class Product
{
// ...
/**
* @ORM\ManyToOne(targetEntity="Category", inversedBy="products")
* @ORM\JoinColumn(name="category_id", referencedColumnName="id")
*/
private $category;
}

Finally, now that you've added a new property to both the Category and Product classes, tell Doctrine
to generate the missing getter and setter methods for you:
Listing 10-33

1 $ php bin/console doctrine:generate:entities AppBundle

Ignore the Doctrine metadata for a moment. You now have two classes - Category and Product with a
natural one-to-many relationship. The Category class holds an array of Product objects and the Product
object can hold one Category object. In other words - you've built your classes in a way that makes sense
for your needs. The fact that the data needs to be persisted to a database is always secondary.
Now, look at the metadata above the $category property on the Product class. The information here
tells Doctrine that the related class is Category and that it should store the id of the category record
on a category_id field that lives on the product table. In other words, the related Category object will
be stored on the $category property, but behind the scenes, Doctrine will persist this relationship by
storing the category's id value on a category_id column of the product table.

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The metadata above the $products property of the Category object is less important, and simply tells
Doctrine to look at the Product.category property to figure out how the relationship is mapped.
Before you continue, be sure to tell Doctrine to add the new category table, and product.category_id
column, and new foreign key:
Listing 10-34

1 $ php bin/console doctrine:schema:update --force

This command should only be used during development. For a more robust method of
systematically updating your production database, read about migrations15.

Saving Related Entities
Now you can see this new code in action! Imagine you're inside a controller:
Listing 10-35

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32

// ...
use AppBundle\Entity\Category;
use AppBundle\Entity\Product;
use Symfony\Component\HttpFoundation\Response;
class DefaultController extends Controller
{
public function createProductAction()
{
$category = new Category();
$category->setName('Computer Peripherals');
$product = new Product();
$product->setName('Keyboard');
$product->setPrice(19.99);
$product->setDescription('Ergonomic and stylish!');

// relate this product to the category
$product->setCategory($category);
$em = $this->getDoctrine()->getManager();
$em->persist($category);
$em->persist($product);
$em->flush();
return new Response(
'Saved new product with id: '.$product->getId()
.' and new category with id: '.$category->getId()
);
}
}

Now, a single row is added to both the category and product tables. The product.category_id column
for the new product is set to whatever the id is of the new category. Doctrine manages the persistence of
this relationship for you.

15. https://symfony.com/doc/current/bundles/DoctrineMigrationsBundle/index.html

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Fetching Related Objects
When you need to fetch associated objects, your workflow looks just like it did before. First, fetch a
$product object and then access its related Category object:
Listing 10-36

1 public function showAction($productId)
2 {
3
$product = $this->getDoctrine()
4
->getRepository('AppBundle:Product')
5
->find($productId);
6
7
$categoryName = $product->getCategory()->getName();
8
9
// ...
10 }

In this example, you first query for a Product object based on the product's id. This issues a query for
just the product data and hydrates the $product object with that data. Later, when you call $product>getCategory()->getName(), Doctrine silently makes a second query to find the Category that's related
to this Product. It prepares the $category object and returns it to you.

What's important is the fact that you have easy access to the product's related category, but the category
data isn't actually retrieved until you ask for the category (i.e. it's "lazily loaded").
You can also query in the other direction:
Listing 10-37

1 public function showProductsAction($categoryId)
2 {
3
$category = $this->getDoctrine()
4
->getRepository('AppBundle:Category')
5
->find($categoryId);
6
7
$products = $category->getProducts();
8
9
// ...
10 }

In this case, the same things occur: you first query out for a single Category object, and then Doctrine
makes a second query to retrieve the related Product objects, but only once/if you ask for them (i.e. when

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you call ->getProducts()). The $products variable is an array of all Product objects that relate to the
given Category object via their category_id value.

Relationships and Proxy Classes
This "lazy loading" is possible because, when necessary, Doctrine returns a "proxy" object in place
of the true object. Look again at the above example:
Listing 10-38

1
2
3
4
5
6
7
8
9

$product = $this->getDoctrine()
->getRepository('AppBundle:Product')
->find($productId);
$category = $product->getCategory();

// prints "Proxies\AppBundleEntityCategoryProxy"
dump(get_class($category));
die();

This proxy object extends the true Category object, and looks and acts exactly like it. The
difference is that, by using a proxy object, Doctrine can delay querying for the real Category data
until you actually need that data (e.g. until you call $category->getName()).
The proxy classes are generated by Doctrine and stored in the cache directory. And though you'll
probably never even notice that your $category object is actually a proxy object, it's important to
keep it in mind.
In the next section, when you retrieve the product and category data all at once (via a join),
Doctrine will return the true Category object, since nothing needs to be lazily loaded.

Joining Related Records
In the above examples, two queries were made - one for the original object (e.g. a Category) and one for
the related object(s) (e.g. the Product objects).
Remember that you can see all of the queries made during a request via the web debug toolbar.

Of course, if you know up front that you'll need to access both objects, you can avoid the second query
by issuing a join in the original query. Add the following method to the ProductRepository class:
Listing 10-39

1 // src/AppBundle/Entity/ProductRepository.php
2 public function findOneByIdJoinedToCategory($productId)
3 {
4
$query = $this->getEntityManager()
5
->createQuery(
6
'SELECT p, c FROM AppBundle:Product p
7
JOIN p.category c
8
WHERE p.id = :id'
9
)->setParameter('id', $productId);
10
11
try {
12
return $query->getSingleResult();
13
} catch (\Doctrine\ORM\NoResultException $e) {
14
return null;

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15
16 }

}

Now, you can use this method in your controller to query for a Product object and its related Category
with just one query:
Listing 10-40

1 public function showAction($productId)
2 {
3
$product = $this->getDoctrine()
4
->getRepository('AppBundle:Product')
5
->findOneByIdJoinedToCategory($productId);
6
7
$category = $product->getCategory();
8
9
// ...
10 }

More Information on Associations
This section has been an introduction to one common type of entity relationship, the one-to-many
relationship. For more advanced details and examples of how to use other types of relations (e.g. one-toone, many-to-many), see Doctrine's Association Mapping Documentation16.
If you're using annotations, you'll need to prepend all annotations with ORM\ (e.g. ORM\OneToMany),
which is not reflected in Doctrine's documentation. You'll also need to include the use
Doctrine\ORM\Mapping as ORM; statement, which imports the ORM annotations prefix.

Configuration
Doctrine is highly configurable, though you probably won't ever need to worry about most of its options.
To find out more about configuring Doctrine, see the Doctrine section of the config reference.

Lifecycle Callbacks
Sometimes, you need to perform an action right before or after an entity is inserted, updated, or deleted.
These types of actions are known as "lifecycle" callbacks, as they're callback methods that you need to
execute during different stages of the lifecycle of an entity (e.g. the entity is inserted, updated, deleted,
etc).
If you're using annotations for your metadata, start by enabling the lifecycle callbacks. This is not
necessary if you're using YAML or XML for your mapping.
Listing 10-41

1 /**
2 * @ORM\Entity()
3 * @ORM\HasLifecycleCallbacks()
4 */
5 class Product
6 {

16. http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/association-mapping.html

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7
8 }

// ...

Now, you can tell Doctrine to execute a method on any of the available lifecycle events. For example,
suppose you want to set a createdAt date column to the current date, only when the entity is first
persisted (i.e. inserted):
Listing 10-42

1
2
3
4
5
6
7
8
9

// src/AppBundle/Entity/Product.php
/**
* @ORM\PrePersist
*/
public function setCreatedAtValue()
{
$this->createdAt = new \DateTime();
}

The above example assumes that you've created and mapped a createdAt property (not shown
here).

Now, right before the entity is first persisted, Doctrine will automatically call this method and the
createdAt field will be set to the current date.
There are several other lifecycle events that you can hook into. For more information on other lifecycle
events and lifecycle callbacks in general, see Doctrine's Lifecycle Events documentation17.

Lifecycle Callbacks and Event Listeners
Notice that the setCreatedAtValue() method receives no arguments. This is always the case
for lifecycle callbacks and is intentional: lifecycle callbacks should be simple methods that are
concerned with internally transforming data in the entity (e.g. setting a created/updated field,
generating a slug value).
If you need to do some heavier lifting - like performing logging or sending an email - you should
register an external class as an event listener or subscriber and give it access to whatever resources
you need. For more information, see How to Register Event Listeners and Subscribers.

Doctrine Field Types Reference
Doctrine comes with numerous field types available. Each of these maps a PHP data type to a specific
column type in whatever database you're using. For each field type, the Column can be configured further,
setting the length, nullable behavior, name and other options. To see a list of all available types and
more information, see Doctrine's Mapping Types documentation18.

17. http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/events.html#lifecycle-events
18. http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/basic-mapping.html#property-mapping

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Summary
With Doctrine, you can focus on your objects and how they're used in your application and worry about
database persistence second. This is because Doctrine allows you to use any PHP object to hold your data
and relies on mapping metadata information to map an object's data to a particular database table.
And even though Doctrine revolves around a simple concept, it's incredibly powerful, allowing you to
create complex queries and subscribe to events that allow you to take different actions as objects go
through their persistence lifecycle.

Learn more
For more information about Doctrine, see the Doctrine section of the cookbook. Some useful articles
might be:





How to use Doctrine Extensions: Timestampable, Sluggable, Translatable, etc.
Console Commands
DoctrineFixturesBundle19
DoctrineMongoDBBundle20

19. https://symfony.com/doc/current/bundles/DoctrineFixturesBundle/index.html
20. https://symfony.com/doc/current/bundles/DoctrineMongoDBBundle/index.html

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Chapter 11

Databases and Propel
Propel is an open-source Object-Relational Mapping (ORM) for PHP which implements the ActiveRecord
pattern1. It allows you to access your database using a set of objects, providing a simple API for storing
and retrieving data. Propel uses PDO as an abstraction layer and code generation to remove the burden
of runtime introspection.
A few years ago, Propel was a very popular alternative to Doctrine. However, its popularity has rapidly
declined and that's why the Symfony book no longer includes the Propel documentation. Read the official
PropelBundle documentation2 to learn how to integrate Propel into your Symfony projects.

1. https://en.wikipedia.org/wiki/Active_record_pattern
2. https://github.com/propelorm/PropelBundle/blob/1.4/Resources/doc/index.markdown

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Chapter 12

Testing
Whenever you write a new line of code, you also potentially add new bugs. To build better and more
reliable applications, you should test your code using both functional and unit tests.

The PHPUnit Testing Framework
Symfony integrates with an independent library - called PHPUnit - to give you a rich testing framework.
This chapter won't cover PHPUnit itself, but it has its own excellent documentation1.
It's recommended to use the latest stable PHPUnit version (you will have to use version 4.2 or
higher to test the Symfony core code itself).

Each test - whether it's a unit test or a functional test - is a PHP class that should live in the tests/
directory of your application. If you follow this rule, then you can run all of your application's tests with
the following command:
Listing 12-1

1 $ phpunit

PHPunit is configured by the phpunit.xml.dist file in the root of your Symfony application.
Code coverage can be generated with the --coverage-* options, see the help information that is
shown when using --help for more information.

1. https://phpunit.de/manual/current/en/

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Unit Tests
A unit test is a test against a single PHP class, also called a unit. If you want to test the overall behavior of
your application, see the section about Functional Tests.
Writing Symfony unit tests is no different from writing standard PHPUnit unit tests. Suppose, for
example, that you have an incredibly simple class called Calculator in the Util/ directory of the app
bundle:
Listing 12-2

1
2
3
4
5
6
7
8
9
10

// src/AppBundle/Util/Calculator.php
namespace AppBundle\Util;
class Calculator
{
public function add($a, $b)
{
return $a + $b;
}
}

To test this, create a CalculatorTest file in the tests/AppBundle/Util directory of your bundle:
Listing 12-3

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

// tests/AppBundle/Util/CalculatorTest.php
namespace Tests\AppBundle\Util;
use AppBundle\Util\Calculator;
class CalculatorTest extends \PHPUnit_Framework_TestCase
{
public function testAdd()
{
$calc = new Calculator();
$result = $calc->add(30, 12);

// assert that your calculator added the numbers correctly!
$this->assertEquals(42, $result);
}
}

By convention, the Tests/AppBundle directory should replicate the directory of your bundle for
unit tests. So, if you're testing a class in the AppBundle/Util/ directory, put the test in the tests/
AppBundle/Util/ directory.

Just like in your real application - autoloading is automatically enabled via the autoload.php file (as
configured by default in the phpunit.xml.dist file).
Running tests for a given file or directory is also very easy:
Listing 12-4

1
2
3
4
5
6
7
8

# run all tests of the application
$ phpunit
# run all tests in the Util directory
$ phpunit tests/AppBundle/Util
# run tests for the Calculator class
$ phpunit tests/AppBundle/Util/CalculatorTest.php

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9
10 # run all tests for the entire Bundle
11 $ phpunit tests/AppBundle/

Functional Tests
Functional tests check the integration of the different layers of an application (from the routing to the
views). They are no different from unit tests as far as PHPUnit is concerned, but they have a very specific
workflow:






Make a request;
Test the response;
Click on a link or submit a form;
Test the response;
Rinse and repeat.

Your First Functional Test
Functional tests are simple PHP files that typically live in the tests/AppBundle/Controller directory
for your bundle. If you want to test the pages handled by your PostController class, start by creating a
new PostControllerTest.php file that extends a special WebTestCase class.
As an example, a test could look like this:
Listing 12-5

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

// tests/AppBundle/Controller/PostControllerTest.php
namespace Tests\AppBundle\Controller;
use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
class PostControllerTest extends WebTestCase
{
public function testShowPost()
{
$client = static::createClient();
$crawler = $client->request('GET', '/post/hello-world');
$this->assertGreaterThan(
0,
$crawler->filter('html:contains("Hello World")')->count()
);
}
}

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To run your functional tests, the WebTestCase class bootstraps the kernel of your application. In
most cases, this happens automatically. However, if your kernel is in a non-standard directory,
you'll need to modify your phpunit.xml.dist file to set the KERNEL_DIR environment variable to
the directory of your kernel:
Listing 12-6

1
2
3

4

5

6

7


The createClient() method returns a client, which is like a browser that you'll use to crawl your site:
Listing 12-7

1 $crawler = $client->request('GET', '/post/hello-world');

The request() method (read more about the request method) returns a Crawler2 object which can be
used to select elements in the response, click on links and submit forms.
The Crawler only works when the response is an XML or an HTML document. To get the raw
content response, call $client->getResponse()->getContent().

Click on a link by first selecting it with the crawler using either an XPath expression or a CSS selector,
then use the client to click on it. For example:
Listing 12-8

1
2
3
4
5
6
7
8

$link = $crawler
->filter('a:contains("Greet")') // find all links with the text "Greet"
->eq(1) // select the second link in the list
->link()
;

// and click it
$crawler = $client->click($link);

Submitting a form is very similar: select a form button, optionally override some form values and submit
the corresponding form:
Listing 12-9

1
2
3
4
5
6
7
8

$form = $crawler->selectButton('submit')->form();

// set some values
$form['name'] = 'Lucas';
$form['form_name[subject]'] = 'Hey there!';
// submit the form
$crawler = $client->submit($form);

2. http://api.symfony.com/3.0/Symfony/Component/DomCrawler/Crawler.html

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The form can also handle uploads and contains methods to fill in different types of form fields (e.g.
select() and tick()). For details, see the Forms section below.

Now that you can easily navigate through an application, use assertions to test that it actually does what
you expect it to. Use the Crawler to make assertions on the DOM:
Listing 12-10

1 // Assert that the response matches a given CSS selector.
2 $this->assertGreaterThan(0, $crawler->filter('h1')->count());

Or test against the response content directly if you just want to assert that the content contains some text
or in case that the response is not an XML/HTML document:
Listing 12-11

1 $this->assertContains(
2
'Hello World',
3
$client->getResponse()->getContent()
4 );

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Useful Assertions
To get you started faster, here is a list of the most common and useful test assertions:
Listing 12-12

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31
32
33
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37
38
39
40
41
42
43

use Symfony\Component\HttpFoundation\Response;

// ...
// Assert that there is at least one h2 tag
// with the class "subtitle"
$this->assertGreaterThan(
0,
$crawler->filter('h2.subtitle')->count()
);
// Assert that there are exactly 4 h2 tags on the page
$this->assertCount(4, $crawler->filter('h2'));
// Assert that the "Content-Type" header is "application/json"
$this->assertTrue(
$client->getResponse()->headers->contains(
'Content-Type',
'application/json'
)
);
// Assert that the response content contains a string
$this->assertContains('foo', $client->getResponse()->getContent());
// ...or matches a regex
$this->assertRegExp('/foo(bar)?/', $client->getResponse()->getContent());
// Assert that the response status code is 2xx
$this->assertTrue($client->getResponse()->isSuccessful());
// Assert that the response status code is 404
$this->assertTrue($client->getResponse()->isNotFound());
// Assert a specific 200 status code
$this->assertEquals(
200, // or Symfony\Component\HttpFoundation\Response::HTTP_OK
$client->getResponse()->getStatusCode()
);
// Assert that the response is a redirect to /demo/contact
$this->assertTrue(
$client->getResponse()->isRedirect('/demo/contact')
);
// ...or simply check that the response is a redirect to any URL
$this->assertTrue($client->getResponse()->isRedirect());

Working with the Test Client
The test client simulates an HTTP client like a browser and makes requests into your Symfony
application:
Listing 12-13

1 $crawler = $client->request('GET', '/post/hello-world');

The request() method takes the HTTP method and a URL as arguments and returns a Crawler
instance.
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Hardcoding the request URLs is a best practice for functional tests. If the test generates URLs using
the Symfony router, it won't detect any change made to the application URLs which may impact
the end users.

More about the request() Method:
The full signature of the request() method is:
Listing 12-14

1 request(
2
$method,
3
$uri,
4
array $parameters = array(),
5
array $files = array(),
6
array $server = array(),
7
$content = null,
8
$changeHistory = true
9 )

The server array is the raw values that you'd expect to normally find in the PHP $_SERVER3
superglobal. For example, to set the Content-Type, Referer and X-Requested-With HTTP
headers, you'd pass the following (mind the HTTP_ prefix for non standard headers):
Listing 12-15

1 $client->request(
2
'GET',
3
'/post/hello-world',
4
array(),
5
array(),
6
array(
7
'CONTENT_TYPE'
=> 'application/json',
8
'HTTP_REFERER'
=> '/foo/bar',
9
'HTTP_X-Requested-With' => 'XMLHttpRequest',
10
)
11 );

Use the crawler to find DOM elements in the response. These elements can then be used to click on links
and submit forms:
Listing 12-16

1
2
3
4
5

$link = $crawler->selectLink('Go elsewhere...')->link();
$crawler = $client->click($link);
$form = $crawler->selectButton('validate')->form();
$crawler = $client->submit($form, array('name' => 'Fabien'));

The click() and submit() methods both return a Crawler object. These methods are the best way to
browse your application as it takes care of a lot of things for you, like detecting the HTTP method from
a form and giving you a nice API for uploading files.
You will learn more about the Link and Form objects in the Crawler section below.

3. http://php.net/manual/en/reserved.variables.server.php

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The request method can also be used to simulate form submissions directly or perform more complex
requests. Some useful examples:
Listing 12-17

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2
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21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37

// Directly submit a form (but using the Crawler is easier!)
$client->request('POST', '/submit', array('name' => 'Fabien'));
// Submit a raw JSON string in the request body
$client->request(
'POST',
'/submit',
array(),
array(),
array('CONTENT_TYPE' => 'application/json'),
'{"name":"Fabien"}'
);
// Form submission with a file upload
use Symfony\Component\HttpFoundation\File\UploadedFile;
$photo = new UploadedFile(
'/path/to/photo.jpg',
'photo.jpg',
'image/jpeg',
123
);
$client->request(
'POST',
'/submit',
array('name' => 'Fabien'),
array('photo' => $photo)
);

// Perform a DELETE request and pass HTTP headers
$client->request(
'DELETE',
'/post/12',
array(),
array(),
array('PHP_AUTH_USER' => 'username', 'PHP_AUTH_PW' => 'pa$$word')
);

Last but not least, you can force each request to be executed in its own PHP process to avoid any sideeffects when working with several clients in the same script:
Listing 12-18

1 $client->insulate();

Browsing
The Client supports many operations that can be done in a real browser:
Listing 12-19

1
2
3
4
5
6

$client->back();
$client->forward();
$client->reload();

// Clears all cookies and the history
$client->restart();

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Accessing Internal Objects
If you use the client to test your application, you might want to access the client's internal objects:
Listing 12-20

1 $history = $client->getHistory();
2 $cookieJar = $client->getCookieJar();

You can also get the objects related to the latest request:
Listing 12-21

1
2
3
4
5
6
7
8
9
10
11
12
13

// the HttpKernel request instance
$request = $client->getRequest();
// the BrowserKit request instance
$request = $client->getInternalRequest();
// the HttpKernel response instance
$response = $client->getResponse();
// the BrowserKit response instance
$response = $client->getInternalResponse();
$crawler = $client->getCrawler();

If your requests are not insulated, you can also access the Container and the Kernel:
Listing 12-22

1 $container = $client->getContainer();
2 $kernel = $client->getKernel();

Accessing the Container
It's highly recommended that a functional test only tests the Response. But under certain very rare
circumstances, you might want to access some internal objects to write assertions. In such cases, you can
access the Dependency Injection Container:
Listing 12-23

1 $container = $client->getContainer();

Be warned that this does not work if you insulate the client or if you use an HTTP layer. For a list of
services available in your application, use the debug:container console task.
If the information you need to check is available from the profiler, use it instead.

Accessing the Profiler Data
On each request, you can enable the Symfony profiler to collect data about the internal handling of that
request. For example, the profiler could be used to verify that a given page executes less than a certain
number of database queries when loading.
To get the Profiler for the last request, do the following:
Listing 12-24

1 // enable the profiler for the very next request
2 $client->enableProfiler();

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3
4 $crawler = $client->request('GET', '/profiler');
5
6 // get the profile
7 $profile = $client->getProfile();

For specific details on using the profiler inside a test, see the How to Use the Profiler in a Functional Test
cookbook entry.

Redirecting
When a request returns a redirect response, the client does not follow it automatically. You can examine
the response and force a redirection afterwards with the followRedirect() method:
Listing 12-25

1 $crawler = $client->followRedirect();

If you want the client to automatically follow all redirects, you can force him with the
followRedirects() method:
Listing 12-26

1 $client->followRedirects();

If you pass false to the followRedirects() method, the redirects will no longer be followed:
Listing 12-27

1 $client->followRedirects(false);

The Crawler
A Crawler instance is returned each time you make a request with the Client. It allows you to traverse
HTML documents, select nodes, find links and forms.

Traversing
Like jQuery, the Crawler has methods to traverse the DOM of an HTML/XML document. For example,
the following finds all input[type=submit] elements, selects the last one on the page, and then selects
its immediate parent element:
Listing 12-28

1 $newCrawler = $crawler->filter('input[type=submit]')
2
->last()
3
->parents()
4
->first()
5 ;

Many other methods are also available:
filter('h1.title')
Nodes that match the CSS selector.
filterXpath('h1')
Nodes that match the XPath expression.
eq(1)
Node for the specified index.

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first()
First node.
last()
Last node.
siblings()
Siblings.
nextAll()
All following siblings.
previousAll()
All preceding siblings.
parents()
Returns the parent nodes.
children()
Returns children nodes.
reduce($lambda)
Nodes for which the callable does not return false.
Since each of these methods returns a new Crawler instance, you can narrow down your node selection
by chaining the method calls:
Listing 12-29

1 $crawler
2
->filter('h1')
3
->reduce(function ($node, $i) {
4
if (!$node->getAttribute('class')) {
5
return false;
6
}
7
})
8
->first()
9 ;

Use the count() function to get the number of nodes stored in a Crawler: count($crawler)

Extracting Information
The Crawler can extract information from the nodes:
Listing 12-30

1
2
3
4
5
6
7
8
9
10

// Returns the attribute value for the first node
$crawler->attr('class');
// Returns the node value for the first node
$crawler->text();
//
//
//
//

Extracts an array of attributes for all nodes
(_text returns the node value)
returns an array for each element in crawler,
each with the value and href

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11
12
13
14
15
16

$info = $crawler->extract(array('_text', 'href'));

// Executes a lambda for each node and return an array of results
$data = $crawler->each(function ($node, $i) {
return $node->attr('href');
});

Links
To select links, you can use the traversing methods above or the convenient selectLink() shortcut:
Listing 12-31

1 $crawler->selectLink('Click here');

This selects all links that contain the given text, or clickable images for which the alt attribute contains
the given text. Like the other filtering methods, this returns another Crawler object.
Once you've selected a link, you have access to a special Link object, which has helpful methods specific
to links (such as getMethod() and getUri()). To click on the link, use the Client's click() method and
pass it a Link object:
Listing 12-32

1 $link = $crawler->selectLink('Click here')->link();
2
3 $client->click($link);

Forms
Forms can be selected using their buttons, which can be selected with the selectButton() method, just
like links:
Listing 12-33

1 $buttonCrawlerNode = $crawler->selectButton('submit');

Notice that you select form buttons and not forms as a form can have several buttons; if you use
the traversing API, keep in mind that you must look for a button.

The selectButton() method can select button tags and submit input tags. It uses several parts of the
buttons to find them:
• The value attribute value;
• The id or alt attribute value for images;
• The id or name attribute value for button tags.
Once you have a Crawler representing a button, call the form() method to get a Form instance for the
form wrapping the button node:
Listing 12-34

1 $form = $buttonCrawlerNode->form();

When calling the form() method, you can also pass an array of field values that overrides the default
ones:
Listing 12-35

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1 $form = $buttonCrawlerNode->form(array(
2
'name'
=> 'Fabien',
3
'my_form[subject]' => 'Symfony rocks!',
4 ));

And if you want to simulate a specific HTTP method for the form, pass it as a second argument:
Listing 12-36

1 $form = $buttonCrawlerNode->form(array(), 'DELETE');

The Client can submit Form instances:
Listing 12-37

1 $client->submit($form);

The field values can also be passed as a second argument of the submit() method:
Listing 12-38

1 $client->submit($form, array(
2
'name'
=> 'Fabien',
3
'my_form[subject]' => 'Symfony rocks!',
4 ));

For more complex situations, use the Form instance as an array to set the value of each field individually:
Listing 12-39

1 // Change the value of a field
2 $form['name'] = 'Fabien';
3 $form['my_form[subject]'] = 'Symfony rocks!';

There is also a nice API to manipulate the values of the fields according to their type:
Listing 12-40

1
2
3
4
5
6
7
8

// Select an option or a radio
$form['country']->select('France');
// Tick a checkbox
$form['like_symfony']->tick();
// Upload a file
$form['photo']->upload('/path/to/lucas.jpg');

If you purposefully want to select "invalid" select/radio values, see Selecting Invalid Choice Values.

You can get the values that will be submitted by calling the getValues() method on the Form
object. The uploaded files are available in a separate array returned by getFiles(). The
getPhpValues() and getPhpFiles() methods also return the submitted values, but in the PHP
format (it converts the keys with square brackets notation - e.g. my_form[subject] - to PHP
arrays).

Adding and Removing Forms to a Collection
If you use a Collection of Forms, you can't add fields to an existing form with
$form['task[tags][0][name]'] = 'foo';. This results in an error Unreachable field "…" because
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$form can only be used in order to set values of existing fields. In order to add new fields, you have to
add the values to the raw data array:
Listing 12-41

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16

// Get the form.
$form = $crawler->filter('button')->form();
// Get the raw values.
$values = $form->getPhpValues();
// Add fields to the raw values.
$values['task']['tag'][0]['name'] = 'foo';
$values['task']['tag'][1]['name'] = 'bar';
// Submit the form with the existing and new values.
$crawler = $this->client->request($form->getMethod(), $form->getUri(), $values,
$form->getPhpFiles());
// The 2 tags have been added to the collection.
$this->assertEquals(2, $crawler->filter('ul.tags > li')->count());

Where task[tags][0][name] is the name of a field created with JavaScript.
You can remove an existing field, e.g. a tag:
Listing 12-42

1
2
3
4
5
6
7
8
9
10
11
12

// Get the values of the form.
$values = $form->getPhpValues();
// Remove the first tag.
unset($values['task']['tags'][0]);
// Submit the data.
$crawler = $client->request($form->getMethod(), $form->getUri(),
$values, $form->getPhpFiles());
// The tag has been removed.
$this->assertEquals(0, $crawler->filter('ul.tags > li')->count());

Testing Configuration
The Client used by functional tests creates a Kernel that runs in a special test environment. Since
Symfony loads the app/config/config_test.yml in the test environment, you can tweak any of your
application's settings specifically for testing.
For example, by default, the Swift Mailer is configured to not actually deliver emails in the test
environment. You can see this under the swiftmailer configuration option:
Listing 12-43

1 # app/config/config_test.yml
2
3 # ...
4 swiftmailer:
5
disable_delivery: true

You can also use a different environment entirely, or override the default debug mode (true) by passing
each as options to the createClient() method:
Listing 12-44

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1 $client = static::createClient(array(
2
'environment' => 'my_test_env',
3
'debug'
=> false,
4 ));

If your application behaves according to some HTTP headers, pass them as the second argument of
createClient():
Listing 12-45

1 $client = static::createClient(array(), array(
2
'HTTP_HOST'
=> 'en.example.com',
3
'HTTP_USER_AGENT' => 'MySuperBrowser/1.0',
4 ));

You can also override HTTP headers on a per request basis:
Listing 12-46

1 $client->request('GET', '/', array(), array(), array(
2
'HTTP_HOST'
=> 'en.example.com',
3
'HTTP_USER_AGENT' => 'MySuperBrowser/1.0',
4 ));

The test client is available as a service in the container in the test environment (or wherever the
framework.test option is enabled). This means you can override the service entirely if you need to.

PHPUnit Configuration
Each application has its own PHPUnit configuration, stored in the phpunit.xml.dist file. You can edit
this file to change the defaults or create an phpunit.xml file to set up a configuration for your local
machine only.
Store the phpunit.xml.dist file in your code repository and ignore the phpunit.xml file.

By default, only the tests stored in /tests are run via the phpunit command, as configured in the
phpunit.xml.dist file:
Listing 12-47

1
2
3

4

5

6
tests
7

8

9

10


But you can easily add more directories. For instance, the following configuration adds tests from a
custom lib/tests directory:
Listing 12-48

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1
2
3

4

5

6

7
../lib/tests
8

9

10

11


To include other directories in the code coverage, also edit the section:
Listing 12-49

1
2
3

4

5

6

7
../lib
8

9

10
../lib/tests
11

12

13

14

15


Learn more








The chapter about tests in the Symfony Framework Best Practices
The DomCrawler Component
The CssSelector Component
How to Simulate HTTP Authentication in a Functional Test
How to Test the Interaction of several Clients
How to Use the Profiler in a Functional Test
How to Customize the Bootstrap Process before Running Tests

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Chapter 12: Testing | 135

Chapter 13

Validation
Validation is a very common task in web applications. Data entered in forms needs to be validated. Data
also needs to be validated before it is written into a database or passed to a web service.
Symfony ships with a Validator1 component that makes this task easy and transparent. This component
is based on the JSR303 Bean Validation specification2.

The Basics of Validation
The best way to understand validation is to see it in action. To start, suppose you've created a plain-oldPHP object that you need to use somewhere in your application:
Listing 13-1

1
2
3
4
5
6
7

// src/AppBundle/Entity/Author.php
namespace AppBundle\Entity;
class Author
{
public $name;
}

So far, this is just an ordinary class that serves some purpose inside your application. The goal of
validation is to tell you if the data of an object is valid. For this to work, you'll configure a list of rules
(called constraints) that the object must follow in order to be valid. These rules can be specified via a
number of different formats (YAML, XML, annotations, or PHP).
For example, to guarantee that the $name property is not empty, add the following:
Listing 13-2

1 // src/AppBundle/Entity/Author.php
2
3 // ...
4 use Symfony\Component\Validator\Constraints as Assert;
5

1. https://github.com/symfony/validator
2. http://jcp.org/en/jsr/detail?id=303

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6 class Author
7 {
8
/**
9
* @Assert\NotBlank()
10
*/
11
public $name;
12 }

Protected and private properties can also be validated, as well as "getter" methods (see Constraint
Targets).

Using the validator Service
Next, to actually validate an Author object, use the validate method on the validator service (class
Validator3). The job of the validator is easy: to read the constraints (i.e. rules) of a class and verify
if the data on the object satisfies those constraints. If validation fails, a non-empty list of errors (class
ConstraintViolationList4) is returned. Take this simple example from inside a controller:
Listing 13-3

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

// ...
use Symfony\Component\HttpFoundation\Response;
use AppBundle\Entity\Author;
// ...
public function authorAction()
{
$author = new Author();
// ... do something to the $author object
$validator = $this->get('validator');
$errors = $validator->validate($author);
if (count($errors) > 0) {
/*
* Uses a __toString method on the $errors variable which is a
* ConstraintViolationList object. This gives us a nice string
* for debugging.
*/
$errorsString = (string) $errors;
return new Response($errorsString);
}
return new Response('The author is valid! Yes!');
}

If the $name property is empty, you will see the following error message:
Listing 13-4

1 AppBundle\Author.name:
2
This value should not be blank

3. http://api.symfony.com/3.0/Symfony/Component/Validator/Validator.html
4. http://api.symfony.com/3.0/Symfony/Component/Validator/ConstraintViolationList.html

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If you insert a value into the name property, the happy success message will appear.
Most of the time, you won't interact directly with the validator service or need to worry about
printing out the errors. Most of the time, you'll use validation indirectly when handling submitted
form data. For more information, see the Validation and Forms.

You could also pass the collection of errors into a template:
Listing 13-5

1 if (count($errors) > 0) {
2
return $this->render('author/validation.html.twig', array(
3
'errors' => $errors,
4
));
5 }

Inside the template, you can output the list of errors exactly as needed:
Listing 13-6

1
2
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4
5
6
7

{# app/Resources/views/author/validation.html.twig #}

The author has the following errors



    {% for error in errors %}
  • {{ error.message }}

  • {% endfor %}


Each validation error (called a "constraint violation"), is represented by a ConstraintViolation5
object.

Validation and Forms
The validator service can be used at any time to validate any object. In reality, however, you'll
usually work with the validator indirectly when working with forms. Symfony's form library uses the
validator service internally to validate the underlying object after values have been submitted. The
constraint violations on the object are converted into FormError objects that can easily be displayed with
your form. The typical form submission workflow looks like the following from inside a controller:
Listing 13-7

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// ...
use AppBundle\Entity\Author;
use AppBundle\Form\AuthorType;
use Symfony\Component\HttpFoundation\Request;
// ...
public function updateAction(Request $request)
{
$author = new Author();
$form = $this->createForm(AuthorType::class, $author);
$form->handleRequest($request);
if ($form->isValid()) {
// the validation passed, do something with the $author object

5. http://api.symfony.com/3.0/Symfony/Component/Validator/ConstraintViolation.html

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17
18
19
20
21
22
23 }

return $this->redirectToRoute(...);
}
return $this->render('author/form.html.twig', array(
'form' => $form->createView(),
));

This example uses an AuthorType form class, which is not shown here.

For more information, see the Forms chapter.

Configuration
The Symfony validator is enabled by default, but you must explicitly enable annotations if you're using
the annotation method to specify your constraints:
Listing 13-8

1 # app/config/config.yml
2 framework:
3
validation: { enable_annotations: true }

Constraints
The validator is designed to validate objects against constraints (i.e. rules). In order to validate an
object, simply map one or more constraints to its class and then pass it to the validator service.
Behind the scenes, a constraint is simply a PHP object that makes an assertive statement. In real life,
a constraint could be: 'The cake must not be burned'. In Symfony, constraints are similar: they are
assertions that a condition is true. Given a value, a constraint will tell you if that value adheres to the
rules of the constraint.

Supported Constraints
Symfony packages many of the most commonly-needed constraints:

Basic Constraints
These are the basic constraints: use them to assert very basic things about the value of properties or the
return value of methods on your object.








NotBlank
Blank
NotNull
IsNull
IsTrue
IsFalse
Type

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String Constraints







Email
Length
Url
Regex
Ip
Uuid

Number Constraints
• Range

Comparison Constraints









EqualTo
NotEqualTo
IdenticalTo
NotIdenticalTo
LessThan
LessThanOrEqual
GreaterThan
GreaterThanOrEqual

Date Constraints
• Date
• DateTime
• Time

Collection Constraints








Choice
Collection
Count
UniqueEntity
Language
Locale
Country

File Constraints
• File
• Image

Financial and other Number Constraints







Bic
CardScheme
Currency
Luhn
Iban
Isbn

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• Issn

Other Constraints






Callback
Expression
All
UserPassword
Valid

You can also create your own custom constraints. This topic is covered in the "How to Create a custom
Validation Constraint" article of the cookbook.

Constraint Configuration
Some constraints, like NotBlank, are simple whereas others, like the Choice constraint, have several
configuration options available. Suppose that the Author class has another property called gender that
can be set to either "male", "female" or "other":
Listing 13-9

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// src/AppBundle/Entity/Author.php
// ...
use Symfony\Component\Validator\Constraints as Assert;
class Author
{
/**
* @Assert\Choice(
*
choices = { "male", "female", "other" },
*
message = "Choose a valid gender."
* )
*/
public $gender;

// ...
}

The options of a constraint can always be passed in as an array. Some constraints, however, also allow
you to pass the value of one, "default", option in place of the array. In the case of the Choice constraint,
the choices options can be specified in this way.
Listing 13-10

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13
14

// src/AppBundle/Entity/Author.php
// ...
use Symfony\Component\Validator\Constraints as Assert;
class Author
{
/**
* @Assert\Choice({"male", "female", "other"})
*/
protected $gender;

// ...
}

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This is purely meant to make the configuration of the most common option of a constraint shorter and
quicker.
If you're ever unsure of how to specify an option, either check the API documentation for the constraint
or play it safe by always passing in an array of options (the first method shown above).

Translation Constraint Messages
For information on translating the constraint messages, see Translating Constraint Messages.

Constraint Targets
Constraints can be applied to a class property (e.g. name) or a public getter method (e.g. getFullName).
The first is the most common and easy to use, but the second allows you to specify more complex
validation rules.

Properties
Validating class properties is the most basic validation technique. Symfony allows you to validate private,
protected or public properties. The next listing shows you how to configure the $firstName property of
an Author class to have at least 3 characters.
Listing 13-11

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7
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12
13

// src/AppBundle/Entity/Author.php
// ...
use Symfony\Component\Validator\Constraints as Assert;
class Author
{
/**
* @Assert\NotBlank()
* @Assert\Length(min=3)
*/
private $firstName;
}

Getters
Constraints can also be applied to the return value of a method. Symfony allows you to add a constraint
to any public method whose name starts with "get", "is" or "has". In this guide, these types of methods
are referred to as "getters".
The benefit of this technique is that it allows you to validate your object dynamically. For example,
suppose you want to make sure that a password field doesn't match the first name of the user (for security
reasons). You can do this by creating an isPasswordLegal method, and then asserting that this method
must return true:
Listing 13-12

1
2
3
4
5
6

// src/AppBundle/Entity/Author.php
// ...
use Symfony\Component\Validator\Constraints as Assert;
class Author

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7 {
8
9
10
11
12
13
14
15 }

/**
* @Assert\IsTrue(message = "The password cannot match your first name")
*/
public function isPasswordLegal()
{
// ... return true or false
}

Now, create the isPasswordLegal() method and include the logic you need:
Listing 13-13

1 public function isPasswordLegal()
2 {
3
return $this->firstName !== $this->password;
4 }

The keen-eyed among you will have noticed that the prefix of the getter ("get", "is" or "has") is
omitted in the mapping. This allows you to move the constraint to a property with the same name
later (or vice versa) without changing your validation logic.

Classes
Some constraints apply to the entire class being validated. For example, the Callback constraint is a
generic constraint that's applied to the class itself. When that class is validated, methods specified by that
constraint are simply executed so that each can provide more custom validation.

Validation Groups
So far, you've been able to add constraints to a class and ask whether or not that class passes all
the defined constraints. In some cases, however, you'll need to validate an object against only some
constraints on that class. To do this, you can organize each constraint into one or more "validation
groups", and then apply validation against just one group of constraints.
For example, suppose you have a User class, which is used both when a user registers and when a user
updates their contact information later:
Listing 13-14

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10
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12
13
14
15

// src/AppBundle/Entity/User.php
namespace AppBundle\Entity;
use Symfony\Component\Security\Core\User\UserInterface;
use Symfony\Component\Validator\Constraints as Assert;
class User implements UserInterface
{
/**
* @Assert\Email(groups={"registration"})
*/
private $email;

/**
* @Assert\NotBlank(groups={"registration"})

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16
17
18
19
20
21
22
23
24 }

* @Assert\Length(min=7, groups={"registration"})
*/
private $password;
/**
* @Assert\Length(min=2)
*/
private $city;

With this configuration, there are three validation groups:
Default
Contains the constraints in the current class and all referenced classes that belong to no other group.
User
Equivalent to all constraints of the User object in the Default group. This is always the name of the
class. The difference between this and Default is explained below.
registration
Contains the constraints on the email and password fields only.
Constraints in the Default group of a class are the constraints that have either no explicit group
configured or that are configured to a group equal to the class name or the string Default.
When validating just the User object, there is no difference between the Default group and the
User group. But, there is a difference if User has embedded objects. For example, imagine User has
an address property that contains some Address object and that you've added the Valid constraint
to this property so that it's validated when you validate the User object.
If you validate User using the Default group, then any constraints on the Address class that are
in the Default group will be used. But, if you validate User using the User validation group, then
only constraints on the Address class with the User group will be validated.
In other words, the Default group and the class name group (e.g. User) are identical, except when
the class is embedded in another object that's actually the one being validated.
If you have inheritance (e.g. User extends BaseUser) and you validate with the class name of the
subclass (i.e. User), then all constraints in the User and BaseUser will be validated. However, if
you validate using the base class (i.e. BaseUser), then only the default constraints in the BaseUser
class will be validated.

To tell the validator to use a specific group, pass one or more group names as the third argument to the
validate() method:
Listing 13-15

1 $errors = $validator->validate($author, null, array('registration'));

If no groups are specified, all constraints that belong to the group Default will be applied.
Of course, you'll usually work with validation indirectly through the form library. For information on
how to use validation groups inside forms, see Validation Groups.

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Group Sequence
In some cases, you want to validate your groups by steps. To do this, you can use the GroupSequence
feature. In this case, an object defines a group sequence, which determines the order groups should be
validated.
For example, suppose you have a User class and want to validate that the username and the password
are different only if all other validation passes (in order to avoid multiple error messages).
Listing 13-16

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28
29

// src/AppBundle/Entity/User.php
namespace AppBundle\Entity;
use Symfony\Component\Security\Core\User\UserInterface;
use Symfony\Component\Validator\Constraints as Assert;

/**
* @Assert\GroupSequence({"User", "Strict"})
*/
class User implements UserInterface
{
/**
* @Assert\NotBlank
*/
private $username;
/**
* @Assert\NotBlank
*/
private $password;
/**
* @Assert\IsTrue(message="The password cannot match your username", groups={"Strict"})
*/
public function isPasswordLegal()
{
return ($this->username !== $this->password);
}
}

In this example, it will first validate all constraints in the group User (which is the same as the Default
group). Only if all constraints in that group are valid, the second group, Strict, will be validated.
As you have already seen in the previous section, the Default group and the group containing the
class name (e.g. User) were identical. However, when using Group Sequences, they are no longer
identical. The Default group will now reference the group sequence, instead of all constraints that
do not belong to any group.
This means that you have to use the {ClassName} (e.g. User) group when specifying a group
sequence. When using Default, you get an infinite recursion (as the Default group references the
group sequence, which will contain the Default group which references the same group sequence,
...).

Group Sequence Providers
Imagine a User entity which can be a normal user or a premium user. When it's a premium user,
some extra constraints should be added to the user entity (e.g. the credit card details). To dynamically

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determine which groups should be activated, you can create a Group Sequence Provider. First, create the
entity and a new constraint group called Premium:
Listing 13-17

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13
14
15
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21
22

// src/AppBundle/Entity/User.php
namespace AppBundle\Entity;
use Symfony\Component\Validator\Constraints as Assert;
class User
{
/**
* @Assert\NotBlank()
*/
private $name;

/**
* @Assert\CardScheme(
*
schemes={"VISA"},
*
groups={"Premium"},
* )
*/
private $creditCard;
// ...
}

Now, change the User class to implement GroupSequenceProviderInterface6 and add the
getGroupSequence()7, method, which should return an array of groups to use:
Listing 13-18

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// src/AppBundle/Entity/User.php
namespace AppBundle\Entity;
// ...
use Symfony\Component\Validator\GroupSequenceProviderInterface;
class User implements GroupSequenceProviderInterface
{
// ...
public function getGroupSequence()
{
$groups = array('User');
if ($this->isPremium()) {
$groups[] = 'Premium';
}
return $groups;
}
}

At last, you have to notify the Validator component that your User class provides a sequence of groups
to be validated:
Listing 13-19

6. http://api.symfony.com/3.0/Symfony/Component/Validator/GroupSequenceProviderInterface.html
7. http://api.symfony.com/3.0/Symfony/Component/Validator/GroupSequenceProviderInterface.html#method_getGroupSequence

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1
2
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5
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7
8
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11
12

// src/AppBundle/Entity/User.php
namespace AppBundle\Entity;
// ...
/**
* @Assert\GroupSequenceProvider
*/
class User implements GroupSequenceProviderInterface
{
// ...
}

Validating Values and Arrays
So far, you've seen how you can validate entire objects. But sometimes, you just want to validate a simple
value - like to verify that a string is a valid email address. This is actually pretty easy to do. From inside a
controller, it looks like this:
Listing 13-20

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// ...
use Symfony\Component\Validator\Constraints as Assert;
// ...
public function addEmailAction($email)
{
$emailConstraint = new Assert\Email();
// all constraint "options" can be set this way
$emailConstraint->message = 'Invalid email address';
// use the validator to validate the value
$errorList = $this->get('validator')->validate(
$email,
$emailConstraint
);
if (0 === count($errorList)) {
// ... this IS a valid email address, do something
} else {
// this is *not* a valid email address
$errorMessage = $errorList[0]->getMessage();

// ... do something with the error
}

// ...
}

By calling validate on the validator, you can pass in a raw value and the constraint object that you want
to validate that value against. A full list of the available constraints - as well as the full class name for each
constraint - is available in the constraints reference section.

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The validate method returns a ConstraintViolationList8 object, which acts just like an array of
errors. Each error in the collection is a ConstraintViolation9 object, which holds the error message on
its getMessage method.

Final Thoughts
The Symfony validator is a powerful tool that can be leveraged to guarantee that the data of any
object is "valid". The power behind validation lies in "constraints", which are rules that you can apply
to properties or getter methods of your object. And while you'll most commonly use the validation
framework indirectly when using forms, remember that it can be used anywhere to validate any object.

Learn more from the Cookbook
• How to Create a custom Validation Constraint

8. http://api.symfony.com/3.0/Symfony/Component/Validator/ConstraintViolationList.html
9. http://api.symfony.com/3.0/Symfony/Component/Validator/ConstraintViolation.html

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Chapter 14

Forms
Dealing with HTML forms is one of the most common - and challenging - tasks for a web developer.
Symfony integrates a Form component that makes dealing with forms easy. In this chapter, you'll build
a complex form from the ground up, learning the most important features of the form library along the
way.
The Symfony Form component is a standalone library that can be used outside of Symfony
projects. For more information, see the Form component documentation on GitHub.

Creating a Simple Form
Suppose you're building a simple todo list application that will need to display "tasks". Because your users
will need to edit and create tasks, you're going to need to build a form. But before you begin, first focus
on the generic Task class that represents and stores the data for a single task:
Listing 14-1

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// src/AppBundle/Entity/Task.php
namespace AppBundle\Entity;
class Task
{
protected $task;
protected $dueDate;
public function getTask()
{
return $this->task;
}
public function setTask($task)
{
$this->task = $task;
}

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18
19
20
21
22
23
24
25
26
27
28 }

public function getDueDate()
{
return $this->dueDate;
}
public function setDueDate(\DateTime $dueDate = null)
{
$this->dueDate = $dueDate;
}

This class is a "plain-old-PHP-object" because, so far, it has nothing to do with Symfony or any other
library. It's quite simply a normal PHP object that directly solves a problem inside your application (i.e.
the need to represent a task in your application). Of course, by the end of this chapter, you'll be able to
submit data to a Task instance (via an HTML form), validate its data, and persist it to the database.

Building the Form
Now that you've created a Task class, the next step is to create and render the actual HTML form. In
Symfony, this is done by building a form object and then rendering it in a template. For now, this can all
be done from inside a controller:
Listing 14-2

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// src/AppBundle/Controller/DefaultController.php
namespace AppBundle\Controller;
use
use
use
use
use
use

AppBundle\Entity\Task;
Symfony\Bundle\FrameworkBundle\Controller\Controller;
Symfony\Component\HttpFoundation\Request;
Symfony\Component\Form\Extension\Core\Type\TextType;
Symfony\Component\Form\Extension\Core\Type\DateType;
Symfony\Component\Form\Extension\Core\Type\SubmitType;

class DefaultController extends Controller
{
public function newAction(Request $request)
{
// create a task and give it some dummy data for this example
$task = new Task();
$task->setTask('Write a blog post');
$task->setDueDate(new \DateTime('tomorrow'));
$form = $this->createFormBuilder($task)
->add('task', TextType::class)
->add('dueDate', DateType::class)
->add('save', SubmitType::class, array('label' => 'Create Task'))
->getForm();
return $this->render('default/new.html.twig', array(
'form' => $form->createView(),
));
}
}

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This example shows you how to build your form directly in the controller. Later, in the "Creating
Form Classes" section, you'll learn how to build your form in a standalone class, which is
recommended as your form becomes reusable.

Creating a form requires relatively little code because Symfony form objects are built with a "form
builder". The form builder's purpose is to allow you to write simple form "recipes", and have it do all the
heavy-lifting of actually building the form.
In this example, you've added two fields to your form - task and dueDate - corresponding to the task and
dueDate properties of the Task class. You've also assigned each a "type" (e.g. TextType and DateType),
represented by its fully qualified class name. Among other things, it determines which HTML form tag(s)
is rendered for that field.
Finally, you added a submit button with a custom label for submitting the form to the server.
Symfony comes with many built-in types that will be discussed shortly (see Built-in Field Types).

Rendering the Form
Now that the form has been created, the next step is to render it. This is done by passing a special form
"view" object to your template (notice the $form->createView() in the controller above) and using a set
of form helper functions:
Listing 14-3

1
2
3
4

{#
{{
{{
{{

app/Resources/views/default/new.html.twig #}
form_start(form) }}
form_widget(form) }}
form_end(form) }}

This example assumes that you submit the form in a "POST" request and to the same URL that it
was displayed in. You will learn later how to change the request method and the target URL of the
form.

That's it! Just three lines are needed to render the complete form:
form_start(form)
Renders the start tag of the form, including the correct enctype attribute when using file uploads.
form_widget(form)
Renders all the fields, which includes the field element itself, a label and any validation error
messages for the field.
form_end(form)
Renders the end tag of the form and any fields that have not yet been rendered, in case you rendered
each field yourself. This is useful for rendering hidden fields and taking advantage of the automatic
CSRF Protection.
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As easy as this is, it's not very flexible (yet). Usually, you'll want to render each form field individually so you
can control how the form looks. You'll learn how to do that in the "Rendering a Form in a Template" section.

Before moving on, notice how the rendered task input field has the value of the task property from the
$task object (i.e. "Write a blog post"). This is the first job of a form: to take data from an object and
translate it into a format that's suitable for being rendered in an HTML form.
The form system is smart enough to access the value of the protected task property via the
getTask() and setTask() methods on the Task class. Unless a property is public, it must have
a "getter" and "setter" method so that the Form component can get and put data onto the
property. For a boolean property, you can use an "isser" or "hasser" method (e.g. isPublished()
or hasReminder()) instead of a getter (e.g. getPublished() or getReminder()).

Handling Form Submissions
The second job of a form is to translate user-submitted data back to the properties of an object. To make
this happen, the submitted data from the user must be written into the Form object. Add the following
functionality to your controller:
Listing 14-4

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25
26

// ...
use Symfony\Component\HttpFoundation\Request;
public function newAction(Request $request)
{
// just setup a fresh $task object (remove the dummy data)
$task = new Task();
$form = $this->createFormBuilder($task)
->add('task', TextType::class)
->add('dueDate', DateType::class)
->add('save', SubmitType::class, array('label' => 'Create Task'))
->getForm();
$form->handleRequest($request);
if ($form->isSubmitted() && $form->isValid()) {
// ... perform some action, such as saving the task to the database
return $this->redirectToRoute('task_success');
}
return $this->render('default/new.html.twig', array(
'form' => $form->createView(),
));
}

Be aware that the createView() method should be called after handleRequest is called.
Otherwise, changes done in the *_SUBMIT events aren't applied to the view (like validation errors).

This controller follows a common pattern for handling forms, and has three possible paths:
1. When initially loading the page in a browser, the form is simply created and rendered.
handleRequest()1 recognizes that the form was not submitted and does nothing.
isSubmitted()2 returns false if the form was not submitted.
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2. When the user submits the form, handleRequest()3 recognizes this and immediately writes the
submitted data back into the task and dueDate properties of the $task object. Then this object
is validated. If it is invalid (validation is covered in the next section), isValid()4 returns false,
so the form is rendered together with all validation errors;
3. When the user submits the form with valid data, the submitted data is again written into the
form, but this time isValid()5 returns true. Now you have the opportunity to perform some
actions using the $task object (e.g. persisting it to the database) before redirecting the user to
some other page (e.g. a "thank you" or "success" page).
Redirecting a user after a successful form submission prevents the user from being able
to hit the "Refresh" button of their browser and re-post the data.

If you need more control over exactly when your form is submitted or which data is passed to it, you can use
the submit()6 for this. Read more about it in the cookbook.

Submitting Forms with Multiple Buttons
When your form contains more than one submit button, you will want to check which of the buttons was
clicked to adapt the program flow in your controller. To do this, add a second button with the caption
"Save and add" to your form:
Listing 14-5

1 $form = $this->createFormBuilder($task)
2
->add('task', TextType::class)
3
->add('dueDate', DateType::class)
4
->add('save', SubmitType::class, array('label' => 'Create Task'))
5
->add('saveAndAdd', SubmitType::class, array('label' => 'Save and Add'))
6
->getForm();

In your controller, use the button's isClicked()7 method for querying if the "Save and add" button was
clicked:
Listing 14-6

1 if ($form->isValid()) {
2
// ... perform some action, such as saving the task to the database
3
4
$nextAction = $form->get('saveAndAdd')->isClicked()
5
? 'task_new'
6
: 'task_success';
7
8
return $this->redirectToRoute($nextAction);
9 }

1. http://api.symfony.com/3.0/Symfony/Component/Form/FormInterface.html#method_handleRequest
2. http://api.symfony.com/3.0/Symfony/Component/Form/FormInterface.html#method_isSubmitted
3. http://api.symfony.com/3.0/Symfony/Component/Form/FormInterface.html#method_handleRequest
4. http://api.symfony.com/3.0/Symfony/Component/Form/FormInterface.html#method_isValid
5. http://api.symfony.com/3.0/Symfony/Component/Form/FormInterface.html#method_isValid
6. http://api.symfony.com/3.0/Symfony/Component/Form/FormInterface.html#method_submit
7. http://api.symfony.com/3.0/Symfony/Component/Form/ClickableInterface.html#method_isClicked

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Form Validation
In the previous section, you learned how a form can be submitted with valid or invalid data. In Symfony,
validation is applied to the underlying object (e.g. Task). In other words, the question isn't whether the
"form" is valid, but whether or not the $task object is valid after the form has applied the submitted data
to it. Calling $form->isValid() is a shortcut that asks the $task object whether or not it has valid data.
Validation is done by adding a set of rules (called constraints) to a class. To see this in action, add
validation constraints so that the task field cannot be empty and the dueDate field cannot be empty and
must be a valid DateTime object.
Listing 14-7

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

// src/AppBundle/Entity/Task.php
namespace AppBundle\Entity;
use Symfony\Component\Validator\Constraints as Assert;
class Task
{
/**
* @Assert\NotBlank()
*/
public $task;

/**
* @Assert\NotBlank()
* @Assert\Type("\DateTime")
*/
protected $dueDate;
}

That's it! If you re-submit the form with invalid data, you'll see the corresponding errors printed out with
the form.

HTML5 Validation
As of HTML5, many browsers can natively enforce certain validation constraints on the client
side. The most common validation is activated by rendering a required attribute on fields that
are required. For browsers that support HTML5, this will result in a native browser message being
displayed if the user tries to submit the form with that field blank.
Generated forms take full advantage of this new feature by adding sensible HTML attributes
that trigger the validation. The client-side validation, however, can be disabled by adding the
novalidate attribute to the form tag or formnovalidate to the submit tag. This is especially useful
when you want to test your server-side validation constraints, but are being prevented by your
browser from, for example, submitting blank fields.
Listing 14-8

1 {# app/Resources/views/default/new.html.twig #}
2 {{ form(form, {'attr': {'novalidate': 'novalidate'}}) }}

Validation is a very powerful feature of Symfony and has its own dedicated chapter.

Validation Groups
If your object takes advantage of validation groups, you'll need to specify which validation group(s) your
form should use:

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Listing 14-9

1 $form = $this->createFormBuilder($users, array(
2
'validation_groups' => array('registration'),
3 ))->add(...);

If you're creating form classes (a good practice), then you'll need to add the following to the
configureOptions() method:
Listing 14-10

1
2
3
4
5
6
7
8

use Symfony\Component\OptionsResolver\OptionsResolver;
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'validation_groups' => array('registration'),
));
}

In both of these cases, only the registration validation group will be used to validate the underlying
object.

Disabling Validation
Sometimes it is useful to suppress the validation of a form altogether. For these cases you can set the
validation_groups option to false:
Listing 14-11

1
2
3
4
5
6
7
8

use Symfony\Component\OptionsResolver\OptionsResolver;
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'validation_groups' => false,
));
}

Note that when you do that, the form will still run basic integrity checks, for example whether an
uploaded file was too large or whether non-existing fields were submitted. If you want to suppress
validation, you can use the POST_SUBMIT event.

Groups based on the Submitted Data
If you need some advanced logic to determine the validation groups (e.g. based on submitted data), you
can set the validation_groups option to an array callback:
Listing 14-12

1
2
3
4
5
6
7
8
9
10
11
12

use Symfony\Component\OptionsResolver\OptionsResolver;

// ...
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'validation_groups' => array(
'AppBundle\Entity\Client',
'determineValidationGroups',
),
));
}

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This will call the static method determineValidationGroups() on the Client class after the form is
submitted, but before validation is executed. The Form object is passed as an argument to that method
(see next example). You can also define whole logic inline by using a Closure:
Listing 14-13

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

use AppBundle\Entity\Client;
use Symfony\Component\Form\FormInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;

// ...
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'validation_groups' => function (FormInterface $form) {
$data = $form->getData();
if (Client::TYPE_PERSON == $data->getType()) {
return array('person');
}
return array('company');
},
));
}

Using the validation_groups option overrides the default validation group which is being used. If you
want to validate the default constraints of the entity as well you have to adjust the option as follows:
Listing 14-14

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

use AppBundle\Entity\Client;
use Symfony\Component\Form\FormInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;

// ...
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'validation_groups' => function (FormInterface $form) {
$data = $form->getData();
if (Client::TYPE_PERSON == $data->getType()) {
return array('Default', 'person');
}
return array('Default', 'company');
},
));
}

You can find more information about how the validation groups and the default constraints work in the
book section about validation groups.

Groups based on the Clicked Button
When your form contains multiple submit buttons, you can change the validation group depending on
which button is used to submit the form. For example, consider a form in a wizard that lets you advance
to the next step or go back to the previous step. Also assume that when returning to the previous step,
the data of the form should be saved, but not validated.
First, we need to add the two buttons to the form:

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Listing 14-15

1 $form = $this->createFormBuilder($task)
2
// ...
3
->add('nextStep', SubmitType::class)
4
->add('previousStep', SubmitType::class)
5
->getForm();

Then, we configure the button for returning to the previous step to run specific validation groups. In this
example, we want it to suppress validation, so we set its validation_groups option to false:
Listing 14-16

1 $form = $this->createFormBuilder($task)
2
// ...
3
->add('previousStep', SubmitType::class, array(
4
'validation_groups' => false,
5
))
6
->getForm();

Now the form will skip your validation constraints. It will still validate basic integrity constraints, such
as checking whether an uploaded file was too large or whether you tried to submit text in a number field.

Built-in Field Types
Symfony comes standard with a large group of field types that cover all of the common form fields and
data types you'll encounter:

Text Fields












TextType
TextareaType
EmailType
IntegerType
MoneyType
NumberType
PasswordType
PercentType
SearchType
UrlType
RangeType

Choice Fields








ChoiceType
EntityType
CountryType
LanguageType
LocaleType
TimezoneType
CurrencyType

Date and Time Fields
• DateType
• DateTimeType
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• TimeType
• BirthdayType

Other Fields
• CheckboxType
• FileType
• RadioType

Field Groups
• CollectionType
• RepeatedType

Hidden Fields
• HiddenType

Buttons
• ButtonType
• ResetType
• SubmitType

Base Fields
• FormType
You can also create your own custom field types. This topic is covered in the "How to Create a Custom
Form Field Type" article of the cookbook.

Field Type Options
Each field type has a number of options that can be used to configure it. For example, the dueDate field
is currently being rendered as 3 select boxes. However, the DateType can be configured to be rendered as
a single text box (where the user would enter the date as a string in the box):
Listing 14-17

1 ->add('dueDate', DateType::class, array('widget' => 'single_text'))

Each field type has a number of different options that can be passed to it. Many of these are specific to
the field type and details can be found in the documentation for each type.

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The required Option
The most common option is the required option, which can be applied to any field. By default,
the required option is set to true, meaning that HTML5-ready browsers will apply client-side
validation if the field is left blank. If you don't want this behavior, either disable HTML5 validation
or set the required option on your field to false:
Listing 14-18

1 ->add('dueDate', DateType::class, array(
2
'widget' => 'single_text',
3
'required' => false
4 ))

Also note that setting the required option to true will not result in server-side validation to be
applied. In other words, if a user submits a blank value for the field (either with an old browser or
web service, for example), it will be accepted as a valid value unless you use Symfony's NotBlank
or NotNull validation constraint.
In other words, the required option is "nice", but true server-side validation should always be
used.

The label Option
The label for the form field can be set using the label option, which can be applied to any field:
Listing 14-19

1 ->add('dueDate', DateType::class, array(
2
'widget' => 'single_text',
3
'label' => 'Due Date',
4 ))

The label for a field can also be set in the template rendering the form, see below. If you don't need
a label associated to your input, you can disable it by setting its value to false.

Field Type Guessing
Now that you've added validation metadata to the Task class, Symfony already knows a bit about your
fields. If you allow it, Symfony can "guess" the type of your field and set it up for you. In this example,
Symfony can guess from the validation rules that both the task field is a normal TextType field and the
dueDate field is a DateType field:
Listing 14-20

1 public function newAction()
2 {
3
$task = new Task();
4
5
$form = $this->createFormBuilder($task)
6
->add('task')
7
->add('dueDate', null, array('widget' => 'single_text'))
8
->add('save', SubmitType::class)
9
->getForm();
10 }

The "guessing" is activated when you omit the second argument to the add() method (or if you pass null
to it). If you pass an options array as the third argument (done for dueDate above), these options are
applied to the guessed field.
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If your form uses a specific validation group, the field type guesser will still consider all validation
constraints when guessing your field types (including constraints that are not part of the validation
group(s) being used).

Field Type Options Guessing
In addition to guessing the "type" for a field, Symfony can also try to guess the correct values of a number
of field options.
When these options are set, the field will be rendered with special HTML attributes that provide
for HTML5 client-side validation. However, it doesn't generate the equivalent server-side
constraints (e.g. Assert\Length). And though you'll need to manually add your server-side
validation, these field type options can then be guessed from that information.

required
The required option can be guessed based on the validation rules (i.e. is the field NotBlank or
NotNull) or the Doctrine metadata (i.e. is the field nullable). This is very useful, as your client-side
validation will automatically match your validation rules.
max_length
If the field is some sort of text field, then the max_length option can be guessed from the validation
constraints (if Length or Range is used) or from the Doctrine metadata (via the field's length).

These field options are only guessed if you're using Symfony to guess the field type (i.e. omit or
pass null as the second argument to add()).

If you'd like to change one of the guessed values, you can override it by passing the option in the options
field array:
Listing 14-21

1 ->add('task', null, array('attr' => array('maxlength' => 4)))

Rendering a Form in a Template
So far, you've seen how an entire form can be rendered with just one line of code. Of course, you'll usually
need much more flexibility when rendering:
Listing 14-22

1 {# app/Resources/views/default/new.html.twig #}
2 {{ form_start(form) }}
3
{{ form_errors(form) }}
4
5
{{ form_row(form.task) }}
6
{{ form_row(form.dueDate) }}
7 {{ form_end(form) }}

You already know the form_start() and form_end() functions, but what do the other functions do?
form_errors(form)
Renders any errors global to the whole form (field-specific errors are displayed next to each field).

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form_row(form.dueDate)
Renders the label, any errors, and the HTML form widget for the given field (e.g. dueDate) inside,
by default, a div element.
The majority of the work is done by the form_row helper, which renders the label, errors and HTML
form widget of each field inside a div tag by default. In the Form Theming section, you'll learn how the
form_row output can be customized on many different levels.
You can access the current data of your form via form.vars.value:
Listing 14-23

1 {{ form.vars.value.task }}

Rendering each Field by Hand
The form_row helper is great because you can very quickly render each field of your form (and the
markup used for the "row" can be customized as well). But since life isn't always so simple, you can also
render each field entirely by hand. The end-product of the following is the same as when you used the
form_row helper:
Listing 14-24

1 {{ form_start(form) }}
2
{{ form_errors(form) }}
3
4

5
{{ form_label(form.task) }}
6
{{ form_errors(form.task) }}
7
{{ form_widget(form.task) }}
8

9
10

11
{{ form_label(form.dueDate) }}
12
{{ form_errors(form.dueDate) }}
13
{{ form_widget(form.dueDate) }}
14

15
16

17
{{ form_widget(form.save) }}
18

19
20 {{ form_end(form) }}

If the auto-generated label for a field isn't quite right, you can explicitly specify it:
Listing 14-25

1 {{ form_label(form.task, 'Task Description') }}

Some field types have additional rendering options that can be passed to the widget. These options are
documented with each type, but one common option is attr, which allows you to modify attributes on
the form element. The following would add the task_field class to the rendered input text field:
Listing 14-26

1 {{ form_widget(form.task, {'attr': {'class': 'task_field'}}) }}

If you need to render form fields "by hand" then you can access individual values for fields such as the
id, name and label. For example to get the id:
Listing 14-27

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1 {{ form.task.vars.id }}

To get the value used for the form field's name attribute you need to use the full_name value:
Listing 14-28

1 {{ form.task.vars.full_name }}

Twig Template Function Reference
If you're using Twig, a full reference of the form rendering functions is available in the reference manual.
Read this to know everything about the helpers available and the options that can be used with each.

Changing the Action and Method of a Form
So far, the form_start() helper has been used to render the form's start tag and we assumed that each
form is submitted to the same URL in a POST request. Sometimes you want to change these parameters.
You can do so in a few different ways. If you build your form in the controller, you can use setAction()
and setMethod():
Listing 14-29

1 $form = $this->createFormBuilder($task)
2
->setAction($this->generateUrl('target_route'))
3
->setMethod('GET')
4
->add('task', TextType::class)
5
->add('dueDate', DateType::class)
6
->add('save', SubmitType::class)
7
->getForm();

This example assumes that you've created a route called target_route that points to the controller
that processes the form.

In Creating Form Classes you will learn how to move the form building code into separate classes. When
using an external form class in the controller, you can pass the action and method as form options:
Listing 14-30

1
2
3
4
5
6
7

use AppBundle\Form\Type\TaskType;
// ...
$form = $this->createForm(TaskType::class, $task, array(
'action' => $this->generateUrl('target_route'),
'method' => 'GET',
));

Finally, you can override the action and method in the template by passing them to the form() or the
form_start() helper:
Listing 14-31

1 {# app/Resources/views/default/new.html.twig #}
2 {{ form_start(form, {'action': path('target_route'), 'method': 'GET'}) }}

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If the form's method is not GET or POST, but PUT, PATCH or DELETE, Symfony will insert
a hidden field with the name _method that stores this method. The form will be submitted in a
normal POST request, but Symfony's router is capable of detecting the _method parameter and will
interpret it as a PUT, PATCH or DELETE request. Read the cookbook chapter "How to Use HTTP
Methods beyond GET and POST in Routes" for more information.

Creating Form Classes
As you've seen, a form can be created and used directly in a controller. However, a better practice is
to build the form in a separate, standalone PHP class, which can then be reused anywhere in your
application. Create a new class that will house the logic for building the task form:
Listing 14-32

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

// src/AppBundle/Form/Type/TaskType.php
namespace AppBundle\Form\Type;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Form\Extension\Core\Type\SubmitType;
class TaskType extends AbstractType
{
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('task')
->add('dueDate', null, array('widget' => 'single_text'))
->add('save', SubmitType::class)
;
}
}

This new class contains all the directions needed to create the task form. It can be used to quickly build
a form object in the controller:
Listing 14-33

1
2
3
4
5
6
7
8
9
10

// src/AppBundle/Controller/DefaultController.php
use AppBundle\Form\Type\TaskType;
public function newAction()
{
$task = ...;
$form = $this->createForm(TaskType::class, $task);

// ...
}

Placing the form logic into its own class means that the form can be easily reused elsewhere in your
project. This is the best way to create forms, but the choice is ultimately up to you.

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Setting the data_class
Every form needs to know the name of the class that holds the underlying data (e.g.
AppBundle\Entity\Task). Usually, this is just guessed based off of the object passed to the second
argument to createForm (i.e. $task). Later, when you begin embedding forms, this will no longer
be sufficient. So, while not always necessary, it's generally a good idea to explicitly specify the
data_class option by adding the following to your form type class:
Listing 14-34

1
2
3
4
5
6
7
8

use Symfony\Component\OptionsResolver\OptionsResolver;
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'data_class' => 'AppBundle\Entity\Task',
));
}

When mapping forms to objects, all fields are mapped. Any fields on the form that do not exist on
the mapped object will cause an exception to be thrown.
In cases where you need extra fields in the form (for example: a "do you agree with these terms"
checkbox) that will not be mapped to the underlying object, you need to set the mapped option to
false:
Listing 14-35

1
2
3
4
5
6
7
8
9
10

use Symfony\Component\Form\FormBuilderInterface;
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('task')
->add('dueDate', null, array('mapped' => false))
->add('save', SubmitType::class)
;
}

Additionally, if there are any fields on the form that aren't included in the submitted data, those
fields will be explicitly set to null.
The field data can be accessed in a controller with:
Listing 14-36

1 $form->get('dueDate')->getData();

In addition, the data of an unmapped field can also be modified directly:
Listing 14-37

1 $form->get('dueDate')->setData(new \DateTime());

Defining your Forms as Services
Your form type might have some external dependencies. You can define your form type as a service, and
inject all dependencies you need.

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Services and the service container will be handled later on in this book. Things will be more clear
after reading that chapter.

You might want to use a service defined as app.my_service in your form type. Create a constructor to
your form type to receive the service:
Listing 14-38

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

// src/AppBundle/Form/Type/TaskType.php
namespace AppBundle\Form\Type;
use
use
use
use

App\Utility\MyService;
Symfony\Component\Form\AbstractType;
Symfony\Component\Form\FormBuilderInterface;
Symfony\Component\Form\Extension\Core\Type\SubmitType;

class TaskType extends AbstractType
{
private $myService;
public function __construct(MyService $myService)
{
$this->myService = $myService;
}
public function buildForm(FormBuilderInterface $builder, array $options)
{
// You can now use myService.
$builder
->add('task')
->add('dueDate', null, array('widget' => 'single_text'))
->add('save', SubmitType::class)
;
}
}

Define your form type as a service.
Listing 14-39

1 # src/AppBundle/Resources/config/services.yml
2 services:
3
app.form.type.task:
4
class: AppBundle\Form\Type\TaskType
5
arguments: ["@app.my_service"]
6
tags:
7
- { name: form.type }

Read Creating your Field Type as a Service for more information.

Forms and Doctrine
The goal of a form is to translate data from an object (e.g. Task) to an HTML form and then translate
user-submitted data back to the original object. As such, the topic of persisting the Task object to the
database is entirely unrelated to the topic of forms. But, if you've configured the Task class to be persisted
via Doctrine (i.e. you've added mapping metadata for it), then persisting it after a form submission can
be done when the form is valid:
Listing 14-40

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1 if ($form->isValid()) {
2
$em = $this->getDoctrine()->getManager();
3
$em->persist($task);
4
$em->flush();
5
6
return $this->redirectToRoute('task_success');
7 }

If, for some reason, you don't have access to your original $task object, you can fetch it from the form:
Listing 14-41

1 $task = $form->getData();

For more information, see the Doctrine ORM chapter.
The key thing to understand is that when the form is submitted, the submitted data is transferred to the
underlying object immediately. If you want to persist that data, you simply need to persist the object itself
(which already contains the submitted data).

Embedded Forms
Often, you'll want to build a form that will include fields from many different objects. For example,
a registration form may contain data belonging to a User object as well as many Address objects.
Fortunately, this is easy and natural with the Form component.

Embedding a Single Object
Suppose that each Task belongs to a simple Category object. Start, of course, by creating the Category
object:
Listing 14-42

1
2
3
4
5
6
7
8
9
10
11
12

// src/AppBundle/Entity/Category.php
namespace AppBundle\Entity;
use Symfony\Component\Validator\Constraints as Assert;
class Category
{
/**
* @Assert\NotBlank()
*/
public $name;
}

Next, add a new category property to the Task class:
Listing 14-43

1 // ...
2
3 class Task
4 {
5
// ...
6
7
/**
8
* @Assert\Type(type="AppBundle\Entity\Category")
9
* @Assert\Valid()
10
*/

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11
12
13
14
15
16
17
18
19
20
21
22
23
24 }

protected $category;

// ...
public function getCategory()
{
return $this->category;
}
public function setCategory(Category $category = null)
{
$this->category = $category;
}

The Valid Constraint has been added to the property category. This cascades the validation to
the corresponding entity. If you omit this constraint the child entity would not be validated.

Now that your application has been updated to reflect the new requirements, create a form class so that
a Category object can be modified by the user:
Listing 14-44

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

// src/AppBundle/Form/Type/CategoryType.php
namespace AppBundle\Form\Type;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;
class CategoryType extends AbstractType
{
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder->add('name');
}
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'data_class' => 'AppBundle\Entity\Category',
));
}
}

The end goal is to allow the Category of a Task to be modified right inside the task form itself. To
accomplish this, add a category field to the TaskType object whose type is an instance of the new
CategoryType class:
Listing 14-45

1
2
3
4
5
6
7

use Symfony\Component\Form\FormBuilderInterface;
use AppBundle\Form\Type\CategoryType;
public function buildForm(FormBuilderInterface $builder, array $options)
{
// ...

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8
9 }

$builder->add('category', CategoryType::class);

The fields from CategoryType can now be rendered alongside those from the TaskType class.
Render the Category fields in the same way as the original Task fields:
Listing 14-46

1
2
3
4
5
6
7
8

{# ... #}

Category



{{ form_row(form.category.name) }}


{# ... #}

When the user submits the form, the submitted data for the Category fields are used to construct an
instance of Category, which is then set on the category field of the Task instance.
The Category instance is accessible naturally via $task->getCategory() and can be persisted to the
database or used however you need.

Embedding a Collection of Forms
You can also embed a collection of forms into one form (imagine a Category form with many Product
sub-forms). This is done by using the collection field type.
For more information see the "How to Embed a Collection of Forms" cookbook entry and the
CollectionType reference.

Form Theming
Every part of how a form is rendered can be customized. You're free to change how each form "row"
renders, change the markup used to render errors, or even customize how a textarea tag should be
rendered. Nothing is off-limits, and different customizations can be used in different places.
Symfony uses templates to render each and every part of a form, such as label tags, input tags, error
messages and everything else.
In Twig, each form "fragment" is represented by a Twig block. To customize any part of how a form
renders, you just need to override the appropriate block.
In PHP, each form "fragment" is rendered via an individual template file. To customize any part of how a
form renders, you just need to override the existing template by creating a new one.
To understand how this works, customize the form_row fragment and add a class attribute to the div
element that surrounds each row. To do this, create a new template file that will store the new markup:
Listing 14-47

1 {# app/Resources/views/form/fields.html.twig #}
2 {% block form_row %}
3 {% spaceless %}
4

5
{{ form_label(form) }}
6
{{ form_errors(form) }}
7
{{ form_widget(form) }}
8


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9 {% endspaceless %}
10 {% endblock form_row %}

The form_row form fragment is used when rendering most fields via the form_row function. To tell the
Form component to use your new form_row fragment defined above, add the following to the top of the
template that renders the form:
Listing 14-48

1
2
3
4
5
6
7

{# app/Resources/views/default/new.html.twig #}
{% form_theme form 'form/fields.html.twig' %}
{# or if you want to use multiple themes #}
{% form_theme form 'form/fields.html.twig' 'form/fields2.html.twig' %}
{# ... render the form #}

The form_theme tag (in Twig) "imports" the fragments defined in the given template and uses them when
rendering the form. In other words, when the form_row function is called later in this template, it will
use the form_row block from your custom theme (instead of the default form_row block that ships with
Symfony).
Your custom theme does not have to override all the blocks. When rendering a block which is not
overridden in your custom theme, the theming engine will fall back to the global theme (defined at the
bundle level).
If several custom themes are provided they will be searched in the listed order before falling back to the
global theme.
To customize any portion of a form, you just need to override the appropriate fragment. Knowing exactly
which block or file to override is the subject of the next section.
For a more extensive discussion, see How to Customize Form Rendering.

Form Fragment Naming
In Symfony, every part of a form that is rendered - HTML form elements, errors, labels, etc. - is defined
in a base theme, which is a collection of blocks in Twig and a collection of template files in PHP.
In Twig, every block needed is defined in a single template file (e.g. form_div_layout.html.twig8) that lives
inside the Twig Bridge9. Inside this file, you can see every block needed to render a form and every default
field type.
In PHP, the fragments are individual template files. By default they are located in the Resources/views/
Form directory of the FrameworkBundle (view on GitHub10).
Each fragment name follows the same basic pattern and is broken up into two pieces, separated by a
single underscore character (_). A few examples are:
• form_row - used by form_row to render most fields;
• textarea_widget - used by form_widget to render a textarea field type;
• form_errors - used by form_errors to render errors for a field;
Each fragment follows the same basic pattern: type_part. The type portion corresponds to the field type
being rendered (e.g. textarea, checkbox, date, etc) whereas the part portion corresponds to what is
being rendered (e.g. label, widget, errors, etc). By default, there are 4 possible parts of a form that can
be rendered:

8. https://github.com/symfony/symfony/blob/master/src/Symfony/Bridge/Twig/Resources/views/Form/form_div_layout.html.twig
9. https://github.com/symfony/symfony/tree/master/src/Symfony/Bridge/Twig
10. https://github.com/symfony/symfony/tree/master/src/Symfony/Bundle/FrameworkBundle/Resources/views/Form

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label

(e.g. form_label)

renders the field's label

widget

(e.g. form_widget)

renders the field's HTML representation

errors

(e.g. form_errors)

renders the field's errors

row

(e.g. form_row)

renders the field's entire row (label, widget & errors)

There are actually 2 other parts - rows and rest - but you should rarely if ever need to worry about
overriding them.

By knowing the field type (e.g. textarea) and which part you want to customize (e.g. widget), you can
construct the fragment name that needs to be overridden (e.g. textarea_widget).

Template Fragment Inheritance
In some cases, the fragment you want to customize will appear to be missing. For example, there is no
textarea_errors fragment in the default themes provided with Symfony. So how are the errors for a
textarea field rendered?
The answer is: via the form_errors fragment. When Symfony renders the errors for a textarea type, it
looks first for a textarea_errors fragment before falling back to the form_errors fragment. Each field
type has a parent type (the parent type of textarea is text, its parent is form), and Symfony uses the
fragment for the parent type if the base fragment doesn't exist.
So, to override the errors for only textarea fields, copy the form_errors fragment, rename it to
textarea_errors and customize it. To override the default error rendering for all fields, copy and
customize the form_errors fragment directly.
The "parent" type of each field type is available in the form type reference for each field type.

Global Form Theming
In the above example, you used the form_theme helper (in Twig) to "import" the custom form fragments
into just that form. You can also tell Symfony to import form customizations across your entire project.

Twig
To automatically include the customized blocks from the fields.html.twig template created earlier in
all templates, modify your application configuration file:
Listing 14-49

1 # app/config/config.yml
2 twig:
3
form_themes:
4
- 'form/fields.html.twig'
5
# ...

Any blocks inside the fields.html.twig template are now used globally to define form output.

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Customizing Form Output all in a Single File with Twig
In Twig, you can also customize a form block right inside the template where that customization
is needed:
Listing 14-50

1
2
3
4
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6
7
8
9
10
11
12
13
14
15

{% extends 'base.html.twig' %}

{# import "_self" as the form theme #}
{% form_theme form _self %}
{# make the form fragment customization #}
{% block form_row %}
{# custom field row output #}
{% endblock form_row %}
{% block content %}
{# ... #}
{{ form_row(form.task) }}
{% endblock %}

The {% form_theme form _self %} tag allows form blocks to be customized directly inside
the template that will use those customizations. Use this method to quickly make form output
customizations that will only ever be needed in a single template.
This {% form_theme form _self %} functionality will only work if your template extends
another. If your template does not, you must point form_theme to a separate template.

PHP
To automatically include the customized templates from the app/Resources/views/Form directory
created earlier in all templates, modify your application configuration file:
Listing 14-51

1 # app/config/config.yml
2 framework:
3
templating:
4
form:
5
resources:
6
- 'Form'
7 # ...

Any fragments inside the app/Resources/views/Form directory are now used globally to define form
output.

CSRF Protection
CSRF - or Cross-site request forgery11 - is a method by which a malicious user attempts to make your
legitimate users unknowingly submit data that they don't intend to submit. Fortunately, CSRF attacks
can be prevented by using a CSRF token inside your forms.

11. http://en.wikipedia.org/wiki/Cross-site_request_forgery

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The good news is that, by default, Symfony embeds and validates CSRF tokens automatically for you.
This means that you can take advantage of the CSRF protection without doing anything. In fact, every
form in this chapter has taken advantage of the CSRF protection!
CSRF protection works by adding a hidden field to your form - called _token by default - that contains a
value that only you and your user knows. This ensures that the user - not some other entity - is submitting
the given data. Symfony automatically validates the presence and accuracy of this token.
The _token field is a hidden field and will be automatically rendered if you include the form_end()
function in your template, which ensures that all un-rendered fields are output.
Since the token is stored in the session, a session is started automatically as soon as you render a
form with CSRF protection.

The CSRF token can be customized on a form-by-form basis. For example:
Listing 14-52

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12
13
14
15
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17
18
19

use Symfony\Component\OptionsResolver\OptionsResolver;
class TaskType extends AbstractType
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'data_class'
=> 'AppBundle\Entity\Task',
'csrf_protection' => true,
'csrf_field_name' => '_token',
// a unique key to help generate the secret token
'csrf_token_id'
=> 'task_item',
));
}

// ...
}

To disable CSRF protection, set the csrf_protection option to false. Customizations can also be made
globally in your project. For more information, see the form configuration reference section.
The csrf_token_id option is optional but greatly enhances the security of the generated token by
making it different for each form.

CSRF tokens are meant to be different for every user. This is why you need to be cautious if you
try to cache pages with forms including this kind of protection. For more information, see Caching
Pages that Contain CSRF Protected Forms.

Using a Form without a Class
In most cases, a form is tied to an object, and the fields of the form get and store their data on the
properties of that object. This is exactly what you've seen so far in this chapter with the Task class.

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But sometimes, you may just want to use a form without a class, and get back an array of the submitted
data. This is actually really easy:
Listing 14-53

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8
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11
12
13
14
15
16
17
18
19
20
21
22
23

// make sure you've imported the Request namespace above the class
use Symfony\Component\HttpFoundation\Request;
// ...
public function contactAction(Request $request)
{
$defaultData = array('message' => 'Type your message here');
$form = $this->createFormBuilder($defaultData)
->add('name', TextType::class)
->add('email', EmailType::class)
->add('message', TextareaType::class)
->add('send', SubmitType::class)
->getForm();
$form->handleRequest($request);
if ($form->isValid()) {
// data is an array with "name", "email", and "message" keys
$data = $form->getData();
}

// ... render the form
}

By default, a form actually assumes that you want to work with arrays of data, instead of an object. There
are exactly two ways that you can change this behavior and tie the form to an object instead:
1. Pass an object when creating the form (as the first argument to createFormBuilder or the
second argument to createForm);
2. Declare the data_class option on your form.
If you don't do either of these, then the form will return the data as an array. In this example, since
$defaultData is not an object (and no data_class option is set), $form->getData() ultimately returns
an array.
You can also access POST values (in this case "name") directly through the request object, like so:
Listing 14-54

1 $request->request->get('name');

Be advised, however, that in most cases using the getData() method is a better choice, since it
returns the data (usually an object) after it's been transformed by the Form component.

Adding Validation
The only missing piece is validation. Usually, when you call $form->isValid(), the object is validated
by reading the constraints that you applied to that class. If your form is mapped to an object (i.e. you're
using the data_class option or passing an object to your form), this is almost always the approach you
want to use. See Validation for more details.
But if the form is not mapped to an object and you instead want to retrieve a simple array of your
submitted data, how can you add constraints to the data of your form?
The answer is to setup the constraints yourself, and attach them to the individual fields. The overall
approach is covered a bit more in the validation chapter, but here's a short example:
Listing 14-55

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1
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14
15

use Symfony\Component\Validator\Constraints\Length;
use Symfony\Component\Validator\Constraints\NotBlank;
use Symfony\Component\Form\Extension\Core\Type\TextType;
$builder
->add('firstName', TextType::class, array(
'constraints' => new Length(array('min' => 3)),
))
->add('lastName', TextType::class, array(
'constraints' => array(
new NotBlank(),
new Length(array('min' => 3)),
),
))
;

If you are using validation groups, you need to either reference the Default group when creating
the form, or set the correct group on the constraint you are adding.

Listing 14-56

1 new NotBlank(array('groups' => array('create', 'update'))

Final Thoughts
You now know all of the building blocks necessary to build complex and functional forms for your
application. When building forms, keep in mind that the first goal of a form is to translate data from an
object (Task) to an HTML form so that the user can modify that data. The second goal of a form is to
take the data submitted by the user and to re-apply it to the object.
There's still much more to learn about the powerful world of forms, such as how to handle file uploads
with Doctrine or how to create a form where a dynamic number of sub-forms can be added (e.g. a todo
list where you can keep adding more fields via JavaScript before submitting). See the cookbook for these
topics. Also, be sure to lean on the field type reference documentation, which includes examples of how to
use each field type and its options.

Learn more from the Cookbook









How to Handle File Uploads with Doctrine
FileType Reference
Creating Custom Field Types
How to Customize Form Rendering
How to Dynamically Modify Forms Using Form Events
How to Use Data Transformers
Using CSRF Protection in the Login Form
Caching Pages that Contain CSRF Protected Forms

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Chapter 15

Security
Symfony's security system is incredibly powerful, but it can also be confusing to set up. In this chapter,
you'll learn how to set up your application's security step-by-step, from configuring your firewall and
how you load users to denying access and fetching the User object. Depending on what you need,
sometimes the initial setup can be tough. But once it's done, Symfony's security system is both flexible
and (hopefully) fun to work with.
Since there's a lot to talk about, this chapter is organized into a few big sections:
1. Initial security.yml setup (authentication);
2. Denying access to your app (authorization);
3. Fetching the current User object.
These are followed by a number of small (but still captivating) sections, like logging out and encoding
user passwords.

1) Initial security.yml Setup (Authentication)
The security system is configured in app/config/security.yml. The default configuration looks like
this:
Listing 15-1

1 # app/config/security.yml
2 security:
3
providers:
4
in_memory:
5
memory: ~
6
7
firewalls:
8
dev:
9
pattern: ^/(_(profiler|wdt)|css|images|js)/
10
security: false
11
12
default:
13
anonymous: ~

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The firewalls key is the heart of your security configuration. The dev firewall isn't important, it just
makes sure that Symfony's development tools - which live under URLs like /_profiler and /_wdt aren't
blocked by your security.
You can also match a request against other details of the request (e.g. host). For more information
and examples read How to Restrict Firewalls to a Specific Request.

All other URLs will be handled by the default firewall (no pattern key means it matches all URLs).
You can think of the firewall like your security system, and so it usually makes sense to have just one
main firewall. But this does not mean that every URL requires authentication - the anonymous key takes
care of this. In fact, if you go to the homepage right now, you'll have access and you'll see that you're
"authenticated" as anon.. Don't be fooled by the "Yes" next to Authenticated, you're just an anonymous
user:

You'll learn later how to deny access to certain URLs or controllers.
Security is highly configurable and there's a Security Configuration Reference that shows all of the
options with some extra explanation.

A) Configuring how your Users will Authenticate
The main job of a firewall is to configure how your users will authenticate. Will they use a login form?
HTTP basic authentication? An API token? All of the above?
Let's start with HTTP basic authentication (the old-school prompt) and work up from there. To activate
this, add the http_basic key under your firewall:
Listing 15-2

1 # app/config/security.yml
2 security:
3
# ...
4
5
firewalls:
6
# ...
7
default:
8
anonymous: ~
9
http_basic: ~

Simple! To try this, you need to require the user to be logged in to see a page. To make things interesting,
create a new page at /admin. For example, if you use annotations, create something like this:
Listing 15-3

1 // src/AppBundle/Controller/DefaultController.php
2 // ...

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3
4
5
6
7
8
9
10
11
12
13
14
15
16

use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Component\HttpFoundation\Response;
class DefaultController extends Controller
{
/**
* @Route("/admin")
*/
public function adminAction()
{
return new Response('Admin page!');
}
}

Next, add an access_control entry to security.yml that requires the user to be logged in to access this
URL:
Listing 15-4

1 # app/config/security.yml
2 security:
3
# ...
4
firewalls:
5
# ...
6
default:
7
# ...
8
9
access_control:
10
# require ROLE_ADMIN for /admin*
11
- { path: ^/admin, roles: ROLE_ADMIN }

You'll learn more about this ROLE_ADMIN thing and denying access later in the 2) Denying Access,
Roles and other Authorization section.

Great! Now, if you go to /admin, you'll see the HTTP basic auth prompt:

But who can you login as? Where do users come from?

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Want to use a traditional login form? Great! See How to Build a Traditional Login Form. What
other methods are supported? See the Configuration Reference or build your own.

If your application logs users in via a third-party service such as Google, Facebook or Twitter,
check out the HWIOAuthBundle1 community bundle.

B) Configuring how Users are Loaded
When you type in your username, Symfony needs to load that user's information from somewhere. This
is called a "user provider", and you're in charge of configuring it. Symfony has a built-in way to load users
from the database, or you can create your own user provider.
The easiest (but most limited) way, is to configure Symfony to load hardcoded users directly from the
security.yml file itself. This is called an "in memory" provider, but it's better to think of it as an "in
configuration" provider:
Listing 15-5

1 # app/config/security.yml
2 security:
3
providers:
4
in_memory:
5
memory:
6
users:
7
ryan:
8
password: ryanpass
9
roles: 'ROLE_USER'
10
admin:
11
password: kitten
12
roles: 'ROLE_ADMIN'
13
# ...

Like with firewalls, you can have multiple providers, but you'll probably only need one. If you do
have multiple, you can configure which one provider to use for your firewall under its provider key (e.g.
provider: in_memory).
See How to Use multiple User Providers for all the details about multiple providers setup.

Try to login using username admin and password kitten. You should see an error!
No encoder has been configured for account "Symfony\Component\Security\Core\User\User"
To fix this, add an encoders key:
Listing 15-6

1 # app/config/security.yml
2 security:
3
# ...
4
5
encoders:
6
Symfony\Component\Security\Core\User\User: plaintext
7
# ...

1. https://github.com/hwi/HWIOAuthBundle

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User providers load user information and put it into a User object. If you load users from the database or
some other source, you'll use your own custom User class. But when you use the "in memory" provider, it
gives you a Symfony\Component\Security\Core\User\User object.
Whatever your User class is, you need to tell Symfony what algorithm was used to encode the passwords.
In this case, the passwords are just plaintext, but in a second, you'll change this to use bcrypt.
If you refresh now, you'll be logged in! The web debug toolbar even tells you who you are and what roles
you have:

Because this URL requires ROLE_ADMIN, if you had logged in as ryan, this would deny you access. More
on that later (Securing URL patterns (access_control)).

Loading Users from the Database
If you'd like to load your users via the Doctrine ORM, that's easy! See How to Load Security Users from
the Database (the Entity Provider) for all the details.

C) Encoding the User's Password
Whether your users are stored in security.yml, in a database or somewhere else, you'll want to encode
their passwords. The best algorithm to use is bcrypt:
Listing 15-7

1 # app/config/security.yml
2 security:
3
# ...
4
5
encoders:
6
Symfony\Component\Security\Core\User\User:
7
algorithm: bcrypt
8
cost: 12

Of course, your users' passwords now need to be encoded with this exact algorithm. For hardcoded users,
you can use the built-in command:
Listing 15-8

1 $ php bin/console security:encode-password

It will give you something like this:
Listing 15-9

1 # app/config/security.yml
2 security:
3
# ...
4
5
providers:
6
in_memory:
7
memory:
8
users:

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9
10
11 jli
12
13
14
flCM3V0G

ryan:
password: $2a$12$LCY0MefVIEc3TYPHV9SNnuzOfyr2p/AXIGoQJEDs4am4JwhNz/
roles: 'ROLE_USER'
admin:
password: $2a$12$cyTWeE9kpq1PjqKFiWUZFuCRPwVyAZwm4XzMZ1qPUFl7/
roles: 'ROLE_ADMIN'

Everything will now work exactly like before. But if you have dynamic users (e.g. from a database), how
can you programmatically encode the password before inserting them into the database? Don't worry,
see Dynamically Encoding a Password for details.
Supported algorithms for this method depend on your PHP version, but include the algorithms
returned by the PHP function hash_algos2 as well as a few others (e.g. bcrypt). See the encoders
key in the Security Reference Section for examples.
It's also possible to use different hashing algorithms on a user-by-user basis. See How to Choose the
Password Encoder Algorithm Dynamically for more details.

D) Configuration Done!
Congratulations! You now have a working authentication system that uses HTTP basic auth and loads
users right from the security.yml file.
Your next steps depend on your setup:
• Configure a different way for your users to login, like a login form or something completely
custom;
• Load users from a different source, like the database or some other source;
• Learn how to deny access, load the User object and deal with roles in the Authorization
section.

2) Denying Access, Roles and other Authorization
Users can now login to your app using http_basic or some other method. Great! Now, you need to learn
how to deny access and work with the User object. This is called authorization, and its job is to decide
if a user can access some resource (a URL, a model object, a method call, ...).
The process of authorization has two different sides:
1. The user receives a specific set of roles when logging in (e.g. ROLE_ADMIN).
2. You add code so that a resource (e.g. URL, controller) requires a specific "attribute" (most
commonly a role like ROLE_ADMIN) in order to be accessed.
In addition to roles (e.g. ROLE_ADMIN), you can protect a resource using other attributes/strings
(e.g. EDIT) and use voters or Symfony's ACL system to give these meaning. This might come in
handy if you need to check if user A can "EDIT" some object B (e.g. a Product with id 5). See Access
Control Lists (ACLs): Securing individual Database Objects.

2. http://php.net/manual/en/function.hash-algos.php

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Roles
When a user logs in, they receive a set of roles (e.g. ROLE_ADMIN). In the example above, these are
hardcoded into security.yml. If you're loading users from the database, these are probably stored on a
column in your table.
All roles you assign to a user must begin with the ROLE_ prefix. Otherwise, they won't be handled
by Symfony's security system in the normal way (i.e. unless you're doing something advanced,
assigning a role like FOO to a user and then checking for FOO as described below will not work).

Roles are simple, and are basically strings that you invent and use as needed. For example, if you need
to start limiting access to the blog admin section of your website, you could protect that section using a
ROLE_BLOG_ADMIN role. This role doesn't need to be defined anywhere - you can just start using it.
Make sure every user has at least one role, or your user will look like they're not authenticated. A
common convention is to give every user ROLE_USER.

You can also specify a role hierarchy where some roles automatically mean that you also have other roles.

Add Code to Deny Access
There are two ways to deny access to something:
1. access_control in security.yml allows you to protect URL patterns (e.g. /admin/*). This is easy,
but less flexible;
2. in your code via the security.authorization_checker service.

Securing URL patterns (access_control)
The most basic way to secure part of your application is to secure an entire URL pattern. You saw this
earlier, where anything matching the regular expression ^/admin requires the ROLE_ADMIN role:
Listing 15-10

1 # app/config/security.yml
2 security:
3
# ...
4
5
firewalls:
6
# ...
7
default:
8
# ...
9
10
access_control:
11
# require ROLE_ADMIN for /admin*
12
- { path: ^/admin, roles: ROLE_ADMIN }

This is great for securing entire sections, but you'll also probably want to secure your individual
controllers as well.
You can define as many URL patterns as you need - each is a regular expression. BUT, only one will be
matched. Symfony will look at each starting at the top, and stop as soon as it finds one access_control
entry that matches the URL.
Listing 15-11

1 # app/config/security.yml
2 security:

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# ...

3
4
5
6
7

access_control:
- { path: ^/admin/users, roles: ROLE_SUPER_ADMIN }
- { path: ^/admin, roles: ROLE_ADMIN }

Prepending the path with ^ means that only URLs beginning with the pattern are matched. For example,
a path of simply /admin (without the ^) would match /admin/foo but would also match URLs like /foo/
admin.

Understanding how access_control Works
The access_control section is very powerful, but it can also be dangerous (because it involves
security) if you don't understand how it works. In addition to the URL, the access_control can
match on IP address, host name and HTTP methods. It can also be used to redirect a user to the
https version of a URL pattern.
To learn about all of this, see How Does the Security access_control Work?.

Securing Controllers and other Code
You can easily deny access from inside a controller:
Listing 15-12

1
2
3
4
5
6
7
8
9
10
11
12
13
14

// ...
public function helloAction($name)
{
// The second parameter is used to specify on what object the role is tested.
$this->denyAccessUnlessGranted('ROLE_ADMIN', null, 'Unable to access this page!');

// Old way :
// if (false ===
$this->get('security.authorization_checker')->isGranted('ROLE_ADMIN')) {
//
throw $this->createAccessDeniedException('Unable to access this page!');
// }
// ...
}

In both cases, a special AccessDeniedException3 is thrown, which ultimately triggers a 403 HTTP
response inside Symfony.
That's it! If the user isn't logged in yet, they will be asked to login (e.g. redirected to the login page). If
they are logged in, but do not have the ROLE_ADMIN role, they'll be shown the 403 access denied page
(which you can customize). If they are logged in and have the correct roles, the code will be executed.
Thanks to the SensioFrameworkExtraBundle, you can also secure your controller using annotations:
Listing 15-13

1 // ...
2 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Security;
3
4 /**
5 * @Security("has_role('ROLE_ADMIN')")
6 */

3. http://api.symfony.com/3.0/Symfony/Component/Security/Core/Exception/AccessDeniedException.html

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7 public function helloAction($name)
8 {
9
// ...
10 }

For more information, see the FrameworkExtraBundle documentation4.

Access Control in Templates
If you want to check if the current user has a role inside a template, use the built-in is_granted() helper
function:
Listing 15-14

1 {% if is_granted('ROLE_ADMIN') %}
2
Delete
3 {% endif %}

Securing other Services
Anything in Symfony can be protected by doing something similar to the code used to secure a controller.
For example, suppose you have a service (i.e. a PHP class) whose job is to send emails. You can restrict
use of this class - no matter where it's being used from - to only certain users.
For more information see How to Secure any Service or Method in your Application.

Checking to see if a User is Logged In (IS_AUTHENTICATED_FULLY)
So far, you've checked access based on roles - those strings that start with ROLE_ and are assigned to
users. But if you only want to check if a user is logged in (you don't care about roles), then you can use
IS_AUTHENTICATED_FULLY:
Listing 15-15

1
2
3
4
5
6
7
8
9
10

// ...
public function helloAction($name)
{
if
(!$this->get('security.authorization_checker')->isGranted('IS_AUTHENTICATED_FULLY')) {
throw $this->createAccessDeniedException();
}

// ...
}

You can of course also use this in access_control.

IS_AUTHENTICATED_FULLY isn't a role, but it kind of acts like one, and every user that has successfully
logged in will have this. In fact, there are three special attributes like this:
• IS_AUTHENTICATED_REMEMBERED: All logged in users have this, even if they are logged in
because of a "remember me cookie". Even if you don't use the remember me functionality, you
can use this to check if the user is logged in.
4. https://symfony.com/doc/current/bundles/SensioFrameworkExtraBundle/index.html

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• IS_AUTHENTICATED_FULLY: This is similar to IS_AUTHENTICATED_REMEMBERED, but stronger.
Users who are logged in only because of a "remember me cookie" will have
IS_AUTHENTICATED_REMEMBERED but will not have IS_AUTHENTICATED_FULLY.
• IS_AUTHENTICATED_ANONYMOUSLY: All users (even anonymous ones) have this - this is useful
when whitelisting URLs to guarantee access - some details are in How Does the Security
access_control Work?.
You can also use expressions inside your templates:
Listing 15-16

1 {% if is_granted(expression(
2
'"ROLE_ADMIN" in roles or (user and user.isSuperAdmin())'
3 )) %}
4
Delete
5 {% endif %}

For more details on expressions and security, see Security: Complex Access Controls with Expressions.

Access Control Lists (ACLs): Securing individual Database Objects
Imagine you are designing a blog where users can comment on your posts. You also want a user to be
able to edit their own comments, but not those of other users. Also, as the admin user, you yourself want
to be able to edit all comments.
To accomplish this you have 2 options:
• Voters allow you to write own business logic (e.g. the user can edit this post because they were
the creator) to determine access. You'll probably want this option - it's flexible enough to solve
the above situation.
• ACLs allow you to create a database structure where you can assign any arbitrary user any
access (e.g. EDIT, VIEW) to any object in your system. Use this if you need an admin user to
be able to grant customized access across your system via some admin interface.
In both cases, you'll still deny access using methods similar to what was shown above.

Retrieving the User Object
After authentication, the User object of the current user can be
security.token_storage service. From inside a controller, this will look like:
Listing 15-17

accessed

via

the

1 public function indexAction()
2 {
3
if
4 (!$this->get('security.authorization_checker')->isGranted('IS_AUTHENTICATED_FULLY')) {
5
throw $this->createAccessDeniedException();
6
}
7
8
$user = $this->getUser();
9
10
// the above is a shortcut for this
11
$user = $this->get('security.token_storage')->getToken()->getUser();
}

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The user will be an object and the class of that object will depend on your user provider.

Now you can call whatever methods are on your User object. For example, if your User object has a
getFirstName() method, you could use that:
Listing 15-18

1
2
3
4
5
6
7
8
9

use Symfony\Component\HttpFoundation\Response;
// ...
public function indexAction()
{
// ...
return new Response('Well hi there '.$user->getFirstName());
}

Always Check if the User is Logged In
It's important to check if the user is authenticated first. If they're not, $user will either be null or the
string anon.. Wait, what? Yes, this is a quirk. If you're not logged in, the user is technically the string
anon., though the getUser() controller shortcut converts this to null for convenience.
The point is this: always check to see if the user is logged in before using the User object, and use the
isGranted method (or access_control) to do this:
Listing 15-19

1
2
3
4
5
6
7
8
9

// yay! Use this to see if the user is logged in
if (!$this->get('security.authorization_checker')->isGranted('IS_AUTHENTICATED_FULLY')) {
throw $this->createAccessDeniedException();
}
// boo :(. Never check for the User object to see if they're logged in
if ($this->getUser()) {
}

Retrieving the User in a Template
In a Twig Template this object can be accessed via the app.user key:
Listing 15-20

1 {% if is_granted('IS_AUTHENTICATED_FULLY') %}
2

Username: {{ app.user.username }}


3 {% endif %}

Logging Out
Usually, you'll also want your users to be able to log out. Fortunately, the firewall can handle this
automatically for you when you activate the logout config parameter:
Listing 15-21

1 # app/config/security.yml
2 security:

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3
4
5
6
7
8
9
10

# ...
firewalls:
secured_area:
# ...
logout:
path:
/logout
target: /

Next, you'll need to create a route for this URL (but not a controller):
Listing 15-22

1 # app/config/routing.yml
2 logout:
3
path: /logout

And that's it! By sending a user to /logout (or whatever you configure the path to be), Symfony will unauthenticate the current user.
Once the user has been logged out, they will be redirected to whatever path is defined by the target
parameter above (e.g. the homepage).
If you need to do something more interesting after logging out, you can specify a logout success
handler by adding a success_handler key and pointing it to a service id of a class that implements
LogoutSuccessHandlerInterface5. See Security Configuration Reference.

Notice that when using http-basic authenticated firewalls, there is no real way to log out : the only
way to log out is to have the browser stop sending your name and password on every request.
Clearing your browser cache or restarting your browser usually helps. Some web developer tools
might be helpful here too.

Dynamically Encoding a Password
If, for example, you're storing users in the database, you'll need to encode the users' passwords before
inserting them. No matter what algorithm you configure for your user object, the hashed password can
always be determined in the following way from a controller:
Listing 15-23

1
2
3
4
5
6
7

// whatever *your* User object is
$user = new AppBundle\Entity\User();
$plainPassword = 'ryanpass';
$encoder = $this->container->get('security.password_encoder');
$encoded = $encoder->encodePassword($user, $plainPassword);
$user->setPassword($encoded);

In order for this to work, just make sure that you have the encoder for your user class (e.g.
AppBundle\Entity\User) configured under the encoders key in app/config/security.yml.
The $encoder object also has an isPasswordValid method, which takes the User object as the first
argument and the plain password to check as the second argument.

5. http://api.symfony.com/3.0/Symfony/Component/Security/Http/Logout/LogoutSuccessHandlerInterface.html

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When you allow a user to submit a plaintext password (e.g. registration form, change password
form), you must have validation that guarantees that the password is 4096 characters or fewer.
Read more details in How to implement a simple Registration Form.

Hierarchical Roles
Instead of associating many roles to users, you can define role inheritance rules by creating a role
hierarchy:
Listing 15-24

1 # app/config/security.yml
2 security:
3
# ...
4
5
role_hierarchy:
6
ROLE_ADMIN:
ROLE_USER
7
ROLE_SUPER_ADMIN: [ROLE_ADMIN, ROLE_ALLOWED_TO_SWITCH]

In the above configuration, users with ROLE_ADMIN role will also have the ROLE_USER role. The
ROLE_SUPER_ADMIN role has ROLE_ADMIN, ROLE_ALLOWED_TO_SWITCH and ROLE_USER (inherited from
ROLE_ADMIN).

Stateless Authentication
By default, Symfony relies on a cookie (the Session) to persist the security context of the user. But if you
use certificates or HTTP authentication for instance, persistence is not needed as credentials are available
for each request. In that case, and if you don't need to store anything else between requests, you can
activate the stateless authentication (which means that no cookie will be ever created by Symfony):
Listing 15-25

1 # app/config/security.yml
2 security:
3
# ...
4
5
firewalls:
6
main:
7
http_basic: ~
8
stateless: true

If you use a form login, Symfony will create a cookie even if you set stateless to true.

Checking for Known Security Vulnerabilities in Dependencies
When using lots of dependencies in your Symfony projects, some of them may contain security
vulnerabilities. That's why Symfony includes a command called security:check that checks your
composer.lock file to find any known security vulnerability in your installed dependencies:
Listing 15-26

1 $ php bin/console security:check

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A good security practice is to execute this command regularly to be able to update or replace
compromised dependencies as soon as possible. Internally, this command uses the public security
advisories database6 published by the FriendsOfPHP organization.
The security:check command terminates with a non-zero exit code if any of your dependencies
is affected by a known security vulnerability. Therefore, you can easily integrate it in your build
process.

To enable the security:check command, make sure the SensioDistributionBundle7 is installed.
Listing 15-27

1 $ composer require 'sensio/distribution-bundle'

Final Words
Woh! Nice work! You now know more than the basics of security. The hardest parts are when you have
custom requirements: like a custom authentication strategy (e.g. API tokens), complex authorization
logic and many other things (because security is complex!).
Fortunately, there are a lot of Security Cookbook Articles aimed at describing many of these situations.
Also, see the Security Reference Section. Many of the options don't have specific details, but seeing the
full possible configuration tree may be useful.
Good luck!

Learn More from the Cookbook







Forcing HTTP/HTTPS
Impersonating a User
How to Use Voters to Check User Permissions
Access Control Lists (ACLs)
How to Add "Remember Me" Login Functionality
How to Use multiple User Providers

6. https://github.com/FriendsOfPHP/security-advisories
7. https://packagist.org/packages/sensio/distribution-bundle

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Chapter 16

HTTP Cache
The nature of rich web applications means that they're dynamic. No matter how efficient your
application, each request will always contain more overhead than serving a static file.
And for most Web applications, that's fine. Symfony is lightning fast, and unless you're doing some
serious heavy-lifting, each request will come back quickly without putting too much stress on your server.
But as your site grows, that overhead can become a problem. The processing that's normally performed
on every request should be done only once. This is exactly what caching aims to accomplish.

Caching on the Shoulders of Giants
The most effective way to improve performance of an application is to cache the full output of a page
and then bypass the application entirely on each subsequent request. Of course, this isn't always possible
for highly dynamic websites, or is it? In this chapter, you'll see how the Symfony cache system works and
why this is the best possible approach.
The Symfony cache system is different because it relies on the simplicity and power of the HTTP cache as
defined in the HTTP specification. Instead of reinventing a caching methodology, Symfony embraces the
standard that defines basic communication on the Web. Once you understand the fundamental HTTP
validation and expiration caching models, you'll be ready to master the Symfony cache system.
For the purposes of learning how to cache with Symfony, the subject is covered in four steps:
1. A gateway cache, or reverse proxy, is an independent layer that sits in front of your application.
The reverse proxy caches responses as they're returned from your application and answers
requests with cached responses before they hit your application. Symfony provides its own
reverse proxy, but any reverse proxy can be used.
2. HTTP cache headers are used to communicate with the gateway cache and any other caches
between your application and the client. Symfony provides sensible defaults and a powerful
interface for interacting with the cache headers.
3. HTTP expiration and validation are the two models used for determining whether cached
content is fresh (can be reused from the cache) or stale (should be regenerated by the
application).
4. Edge Side Includes (ESI) allow HTTP cache to be used to cache page fragments (even nested
fragments) independently. With ESI, you can even cache an entire page for 60 minutes, but an
embedded sidebar for only 5 minutes.
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Since caching with HTTP isn't unique to Symfony, many articles already exist on the topic. If you're new
to HTTP caching, Ryan Tomayko's article Things Caches Do1 is highly recommended . Another in-depth
resource is Mark Nottingham's Cache Tutorial2.

Caching with a Gateway Cache
When caching with HTTP, the cache is separated from your application entirely and sits between your
application and the client making the request.
The job of the cache is to accept requests from the client and pass them back to your application. The
cache will also receive responses back from your application and forward them on to the client. The cache
is the "middle-man" of the request-response communication between the client and your application.
Along the way, the cache will store each response that is deemed "cacheable" (See Introduction to HTTP
Caching). If the same resource is requested again, the cache sends the cached response to the client,
ignoring your application entirely.
This type of cache is known as a HTTP gateway cache and many exist such as Varnish3, Squid in reverse
proxy mode4, and the Symfony reverse proxy.

Types of Caches
But a gateway cache isn't the only type of cache. In fact, the HTTP cache headers sent by your application
are consumed and interpreted by up to three different types of caches:
• Browser caches: Every browser comes with its own local cache that is mainly useful for when
you hit "back" or for images and other assets. The browser cache is a private cache as cached
resources aren't shared with anyone else;
• Proxy caches: A proxy is a shared cache as many people can be behind a single one. It's usually
installed by large corporations and ISPs to reduce latency and network traffic;
• Gateway caches: Like a proxy, it's also a shared cache but on the server side. Installed by
network administrators, it makes websites more scalable, reliable and performant.
Gateway caches are sometimes referred to as reverse proxy caches, surrogate caches, or even HTTP
accelerators.

The significance of private versus shared caches will become more obvious when caching responses
containing content that is specific to exactly one user (e.g. account information) is discussed.

Each response from your application will likely go through one or both of the first two cache types. These
caches are outside of your control but follow the HTTP cache directions set in the response.

Symfony Reverse Proxy
Symfony comes with a reverse proxy (also called a gateway cache) written in PHP. Enable it and
cacheable responses from your application will start to be cached right away. Installing it is just as easy.
Each new Symfony application comes with a pre-configured caching kernel (AppCache) that wraps the
default one (AppKernel). The caching Kernel is the reverse proxy.
1. http://2ndscale.com/writings/things-caches-do
2. http://www.mnot.net/cache_docs/
3. https://www.varnish-cache.org/
4. http://wiki.squid-cache.org/SquidFaq/ReverseProxy

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To enable caching, modify the code of a front controller to use the caching kernel:
Listing 16-1

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

// web/app.php
use Symfony\Component\HttpFoundation\Request;
// ...
$kernel = new AppKernel('prod', false);
$kernel->loadClassCache();
// wrap the default AppKernel with the AppCache one
$kernel = new AppCache($kernel);
$request = Request::createFromGlobals();
$response = $kernel->handle($request);
$response->send();
$kernel->terminate($request, $response);

The caching kernel will immediately act as a reverse proxy - caching responses from your application and
returning them to the client.
If you're using the framework.http_method_override option to read the HTTP method from a
_method parameter, see the above link for a tweak you need to make.

The cache kernel has a special getLog() method that returns a string representation of what
happened in the cache layer. In the development environment, use it to debug and validate your
cache strategy:
Listing 16-2

1 error_log($kernel->getLog());

The AppCache object has a sensible default configuration, but it can be finely tuned via a set of options
you can set by overriding the getOptions()5 method:
Listing 16-3

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

// app/AppCache.php
use Symfony\Bundle\FrameworkBundle\HttpCache\HttpCache;
class AppCache extends HttpCache
{
protected function getOptions()
{
return array(
'debug'
'default_ttl'
'private_headers'
'allow_reload'
'allow_revalidate'
'stale_while_revalidate'
'stale_if_error'
);
}
}

=>
=>
=>
=>
=>
=>
=>

false,
0,
array('Authorization', 'Cookie'),
false,
false,
2,
60,

5. http://api.symfony.com/3.0/Symfony/Bundle/FrameworkBundle/HttpCache/HttpCache.html#method_getOptions

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Unless overridden in getOptions(), the debug option will be set to automatically be the debug
value of the wrapped AppKernel.

Here is a list of the main options:
default_ttl
The number of seconds that a cache entry should be considered fresh when no explicit freshness
information is provided in a response. Explicit Cache-Control or Expires headers override this
value (default: 0).
private_headers
Set of request headers that trigger "private" Cache-Control behavior on responses that don't
explicitly state whether the response is public or private via a Cache-Control directive (default:
Authorization and Cookie).
allow_reload
Specifies whether the client can force a cache reload by including a Cache-Control "no-cache"
directive in the request. Set it to true for compliance with RFC 2616 (default: false).
allow_revalidate
Specifies whether the client can force a cache revalidate by including a Cache-Control "max-age=0"
directive in the request. Set it to true for compliance with RFC 2616 (default: false).
stale_while_revalidate
Specifies the default number of seconds (the granularity is the second as the Response TTL precision
is a second) during which the cache can immediately return a stale response while it revalidates it
in the background (default: 2); this setting is overridden by the stale-while-revalidate HTTP
Cache-Control extension (see RFC 5861).
stale_if_error
Specifies the default number of seconds (the granularity is the second) during which the cache can
serve a stale response when an error is encountered (default: 60). This setting is overridden by the
stale-if-error HTTP Cache-Control extension (see RFC 5861).
If debug is true, Symfony automatically adds an X-Symfony-Cache header to the response containing
useful information about cache hits and misses.

Changing from one Reverse Proxy to another
The Symfony reverse proxy is a great tool to use when developing your website or when you deploy
your website to a shared host where you cannot install anything beyond PHP code. But being
written in PHP, it cannot be as fast as a proxy written in C. That's why it is highly recommended
you use Varnish or Squid on your production servers if possible. The good news is that the switch
from one proxy server to another is easy and transparent as no code modification is needed in your
application. Start easy with the Symfony reverse proxy and upgrade later to Varnish when your
traffic increases.
For more information on using Varnish with Symfony, see the How to use Varnish cookbook
chapter.

The performance of the Symfony reverse proxy is independent of the complexity of the application.
That's because the application kernel is only booted when the request needs to be forwarded to it.

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Introduction to HTTP Caching
To take advantage of the available cache layers, your application must be able to communicate which
responses are cacheable and the rules that govern when/how that cache should become stale. This is done
by setting HTTP cache headers on the response.
Keep in mind that "HTTP" is nothing more than the language (a simple text language) that web
clients (e.g. browsers) and web servers use to communicate with each other. HTTP caching is the
part of that language that allows clients and servers to exchange information related to caching.

HTTP specifies four response cache headers that are looked at here:





Cache-Control
Expires
ETag
Last-Modified

The most important and versatile header is the Cache-Control header, which is actually a collection of
various cache information.
Each of the headers will be explained in full detail in the HTTP Expiration, Validation and
Invalidation section.

The Cache-Control Header
The Cache-Control header is unique in that it contains not one, but various pieces of information about
the cacheability of a response. Each piece of information is separated by a comma:
Listing 16-4

1 Cache-Control: private, max-age=0, must-revalidate
2
3 Cache-Control: max-age=3600, must-revalidate

Symfony provides an abstraction around the Cache-Control header to make its creation more
manageable:
Listing 16-5

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

// ...
use Symfony\Component\HttpFoundation\Response;
$response = new Response();

// mark the response as either public or private
$response->setPublic();
$response->setPrivate();
// set the private or shared max age
$response->setMaxAge(600);
$response->setSharedMaxAge(600);
// set a custom Cache-Control directive
$response->headers->addCacheControlDirective('must-revalidate', true);

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If you need to set cache headers for many different controller actions, you might want to look into
the FOSHttpCacheBundle6. It provides a way to define cache headers based on the URL pattern
and other request properties.

Public vs Private Responses
Both gateway and proxy caches are considered "shared" caches as the cached content is shared by more
than one user. If a user-specific response were ever mistakenly stored by a shared cache, it might be
returned later to any number of different users. Imagine if your account information were cached and
then returned to every subsequent user who asked for their account page!
To handle this situation, every response may be set to be public or private:
public
Indicates that the response may be cached by both private and shared caches.
private
Indicates that all or part of the response message is intended for a single user and must not be cached
by a shared cache.
Symfony conservatively defaults each response to be private. To take advantage of shared caches (like the
Symfony reverse proxy), the response will need to be explicitly set as public.

Safe Methods
HTTP caching only works for "safe" HTTP methods (like GET and HEAD). Being safe means that
you never change the application's state on the server when serving the request (you can of course log
information, cache data, etc). This has two very reasonable consequences:
• You should never change the state of your application when responding to a GET or HEAD
request. Even if you don't use a gateway cache, the presence of proxy caches means that any
GET or HEAD request may or may not actually hit your server;
• Don't expect PUT, POST or DELETE methods to cache. These methods are meant to be used
when mutating the state of your application (e.g. deleting a blog post). Caching them would
prevent certain requests from hitting and mutating your application.

Caching Rules and Defaults
HTTP 1.1 allows caching anything by default unless there is an explicit Cache-Control header. In
practice, most caches do nothing when requests have a cookie, an authorization header, use a non-safe
method (i.e. PUT, POST, DELETE), or when responses have a redirect status code.
Symfony automatically sets a sensible and conservative Cache-Control header when none is set by the
developer by following these rules:
• If no cache header is defined (Cache-Control, Expires, ETag or Last-Modified), CacheControl is set to no-cache, meaning that the response will not be cached;
• If Cache-Control is empty (but one of the other cache headers is present), its value is set to
private, must-revalidate;
• But if at least one Cache-Control directive is set, and no public or private directives have
been explicitly added, Symfony adds the private directive automatically (except when smaxage is set).

6. http://foshttpcachebundle.readthedocs.org/

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HTTP Expiration, Validation and Invalidation
The HTTP specification defines two caching models:
• With the expiration model7, you simply specify how long a response should be considered
"fresh" by including a Cache-Control and/or an Expires header. Caches that understand
expiration will not make the same request until the cached version reaches its expiration time
and becomes "stale";
• When pages are really dynamic (i.e. their representation changes often), the validation model8
is often necessary. With this model, the cache stores the response, but asks the server on
each request whether or not the cached response is still valid. The application uses a unique
response identifier (the Etag header) and/or a timestamp (the Last-Modified header) to check
if the page has changed since being cached.
The goal of both models is to never generate the same response twice by relying on a cache to store and
return "fresh" responses. To achieve long caching times but still provide updated content immediately,
cache invalidation is sometimes used.

Reading the HTTP Specification
The HTTP specification defines a simple but powerful language in which clients and servers can
communicate. As a web developer, the request-response model of the specification dominates your
work. Unfortunately, the actual specification document - RFC 26169 - can be difficult to read.
There is an ongoing effort (HTTP Bis10) to rewrite the RFC 2616. It does not describe a new version
of HTTP, but mostly clarifies the original HTTP specification. The organization is also improved as
the specification is split into seven parts; everything related to HTTP caching can be found in two
dedicated parts (P4 - Conditional Requests11 and P6 - Caching: Browser and intermediary caches).
As a web developer, you are strongly urged to read the specification. Its clarity and power - even
more than ten years after its creation - is invaluable. Don't be put-off by the appearance of the spec
- its contents are much more beautiful than its cover.

Expiration
The expiration model is the more efficient and straightforward of the two caching models and should be
used whenever possible. When a response is cached with an expiration, the cache will store the response
and return it directly without hitting the application until it expires.
The expiration model can be accomplished using one of two, nearly identical, HTTP headers: Expires
or Cache-Control.

Expiration with the Expires Header
According to the HTTP specification, "the Expires header field gives the date/time after which the
response is considered stale." The Expires header can be set with the setExpires() Response method.
It takes a DateTime instance as an argument:
Listing 16-6

1 $date = new DateTime();
2 $date->modify('+600 seconds');

7. http://tools.ietf.org/html/rfc2616#section-13.2
8. http://tools.ietf.org/html/rfc2616#section-13.3
9. http://tools.ietf.org/html/rfc2616
10. http://tools.ietf.org/wg/httpbis/
11. http://tools.ietf.org/html/draft-ietf-httpbis-p4-conditional

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3
4 $response->setExpires($date);

The resulting HTTP header will look like this:
Listing 16-7

1 Expires: Thu, 01 Mar 2011 16:00:00 GMT

The setExpires() method automatically converts the date to the GMT timezone as required by
the specification.

Note that in HTTP versions before 1.1 the origin server wasn't required to send the Date header.
Consequently, the cache (e.g. the browser) might need to rely on the local clock to evaluate the Expires
header making the lifetime calculation vulnerable to clock skew. Another limitation of the Expires
header is that the specification states that "HTTP/1.1 servers should not send Expires dates more than
one year in the future."

Expiration with the Cache-Control Header
Because of the Expires header limitations, most of the time, you should use the Cache-Control header
instead. Recall that the Cache-Control header is used to specify many different cache directives. For
expiration, there are two directives, max-age and s-maxage. The first one is used by all caches, whereas
the second one is only taken into account by shared caches:
Listing 16-8

1
2
3
4
5
6

// Sets the number of seconds after which the response
// should no longer be considered fresh
$response->setMaxAge(600);
// Same as above but only for shared caches
$response->setSharedMaxAge(600);

The Cache-Control header would take on the following format (it may have additional directives):
Listing 16-9

1 Cache-Control: max-age=600, s-maxage=600

Validation
When a resource needs to be updated as soon as a change is made to the underlying data, the expiration
model falls short. With the expiration model, the application won't be asked to return the updated
response until the cache finally becomes stale.
The validation model addresses this issue. Under this model, the cache continues to store responses. The
difference is that, for each request, the cache asks the application if the cached response is still valid or if
it needs to be regenerated. If the cache is still valid, your application should return a 304 status code and
no content. This tells the cache that it's ok to return the cached response.
Under this model, you only save CPU if you're able to determine that the cached response is still valid by
doing less work than generating the whole page again (see below for an implementation example).

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The 304 status code means "Not Modified". It's important because with this status code the
response does not contain the actual content being requested. Instead, the response is simply a
light-weight set of directions that tells the cache that it should use its stored version.

Like with expiration, there are two different HTTP headers that can be used to implement the validation
model: ETag and Last-Modified.

Validation with the ETag Header
The ETag header is a string header (called the "entity-tag") that uniquely identifies one representation of
the target resource. It's entirely generated and set by your application so that you can tell, for example,
if the /about resource that's stored by the cache is up-to-date with what your application would return.
An ETag is like a fingerprint and is used to quickly compare if two different versions of a resource are
equivalent. Like fingerprints, each ETag must be unique across all representations of the same resource.
To see a simple implementation, generate the ETag as the md5 of the content:
Listing 16-10

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

// src/AppBundle/Controller/DefaultController.php
namespace AppBundle\Controller;
use Symfony\Component\HttpFoundation\Request;
class DefaultController extends Controller
{
public function homepageAction(Request $request)
{
$response = $this->render('static/homepage.html.twig');
$response->setETag(md5($response->getContent()));
$response->setPublic(); // make sure the response is public/cacheable
$response->isNotModified($request);
return $response;
}
}

The isNotModified()12 method compares the If-None-Match sent with the Request with the ETag
header set on the Response. If the two match, the method automatically sets the Response status code to
304.
The cache sets the If-None-Match header on the request to the ETag of the original cached
response before sending the request back to the app. This is how the cache and server
communicate with each other and decide whether or not the resource has been updated since it
was cached.

This algorithm is simple enough and very generic, but you need to create the whole Response before
being able to compute the ETag, which is sub-optimal. In other words, it saves on bandwidth, but not
CPU cycles.
In the Optimizing your Code with Validation section, you'll see how validation can be used more
intelligently to determine the validity of a cache without doing so much work.

12. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Response.html#method_isNotModified

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Symfony also supports weak ETags by passing true as the second argument to the setEtag()13
method.

Validation with the Last-Modified Header
The Last-Modified header is the second form of validation. According to the HTTP specification,
"The Last-Modified header field indicates the date and time at which the origin server believes the
representation was last modified." In other words, the application decides whether or not the cached
content has been updated based on whether or not it's been updated since the response was cached.
For instance, you can use the latest update date for all the objects needed to compute the resource
representation as the value for the Last-Modified header value:
Listing 16-11

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
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23
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25
26
27
28
29
30
31
32
33

// src/AppBundle/Controller/ArticleController.php
namespace AppBundle\Controller;
// ...
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\Request;
use AppBundle\Entity\Article;
class ArticleController extends Controller
{
public function showAction(Article $article, Request $request)
{
$author = $article->getAuthor();
$articleDate = new \DateTime($article->getUpdatedAt());
$authorDate = new \DateTime($author->getUpdatedAt());
$date = $authorDate > $articleDate ? $authorDate : $articleDate;
$response = new Response();
$response->setLastModified($date);
// Set response as public. Otherwise it will be private by default.
$response->setPublic();
if ($response->isNotModified($request)) {
return $response;
}

// ... do more work to populate the response with the full content
return $response;
}
}

The isNotModified()14 method compares the If-Modified-Since header sent by the request with the
Last-Modified header set on the response. If they are equivalent, the Response will be set to a 304 status
code.

13. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Response.html#method_setEtag
14. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Response.html#method_isNotModified

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The cache sets the If-Modified-Since header on the request to the Last-Modified of the original
cached response before sending the request back to the app. This is how the cache and server
communicate with each other and decide whether or not the resource has been updated since it
was cached.

Optimizing your Code with Validation
The main goal of any caching strategy is to lighten the load on the application. Put another way, the
less you do in your application to return a 304 response, the better. The Response::isNotModified()
method does exactly that by exposing a simple and efficient pattern:
Listing 16-12

1
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30
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34
35
36
37
38
39
40
41

// src/AppBundle/Controller/ArticleController.php
namespace AppBundle\Controller;
// ...
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\Request;
class ArticleController extends Controller
{
public function showAction($articleSlug, Request $request)
{
// Get the minimum information to compute
// the ETag or the Last-Modified value
// (based on the Request, data is retrieved from
// a database or a key-value store for instance)
$article = ...;

// create a Response with an ETag and/or a Last-Modified header
$response = new Response();
$response->setETag($article->computeETag());
$response->setLastModified($article->getPublishedAt());
// Set response as public. Otherwise it will be private by default.
$response->setPublic();
// Check that the Response is not modified for the given Request
if ($response->isNotModified($request)) {
// return the 304 Response immediately
return $response;
}
// do more work here - like retrieving more data
$comments = ...;
// or render a template with the $response you've already started
return $this->render('article/show.html.twig', array(
'article' => $article,
'comments' => $comments
), $response);
}
}

When the Response is not modified, the isNotModified() automatically sets the response status code
to 304, removes the content, and removes some headers that must not be present for 304 responses (see
setNotModified()15).

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Varying the Response
So far, it's been assumed that each URI has exactly one representation of the target resource. By default,
HTTP caching is done by using the URI of the resource as the cache key. If two people request the same
URI of a cacheable resource, the second person will receive the cached version.
Sometimes this isn't enough and different versions of the same URI need to be cached based on one or
more request header values. For instance, if you compress pages when the client supports it, any given
URI has two representations: one when the client supports compression, and one when it does not. This
determination is done by the value of the Accept-Encoding request header.
In this case, you need the cache to store both a compressed and uncompressed version of the response
for the particular URI and return them based on the request's Accept-Encoding value. This is done by
using the Vary response header, which is a comma-separated list of different headers whose values trigger
a different representation of the requested resource:
Listing 16-13

1 Vary: Accept-Encoding, User-Agent

This particular Vary header would cache different versions of each resource based on the URI and
the value of the Accept-Encoding and User-Agent request header.

The Response object offers a clean interface for managing the Vary header:
Listing 16-14

1
2
3
4
5

// set one vary header
$response->setVary('Accept-Encoding');
// set multiple vary headers
$response->setVary(array('Accept-Encoding', 'User-Agent'));

The setVary() method takes a header name or an array of header names for which the response varies.

Expiration and Validation
You can of course use both validation and expiration within the same Response. As expiration wins over
validation, you can easily benefit from the best of both worlds. In other words, by using both expiration
and validation, you can instruct the cache to serve the cached content, while checking back at some
interval (the expiration) to verify that the content is still valid.
You can also define HTTP caching headers for expiration and validation by using annotations. See
the FrameworkExtraBundle documentation16.

More Response Methods
The Response class provides many more methods related to the cache. Here are the most useful ones:
Listing 16-15

1 // Marks the Response stale
2 $response->expire();
3

15. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Response.html#method_setNotModified
16. https://symfony.com/doc/current/bundles/SensioFrameworkExtraBundle/annotations/cache.html

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4 // Force the response to return a proper 304 response with no content
5 $response->setNotModified();

Additionally, most cache-related HTTP headers can be set via the single setCache()17 method:
Listing 16-16

1 // Set cache settings in one call
2 $response->setCache(array(
3
'etag'
=> $etag,
4
'last_modified' => $date,
5
'max_age'
=> 10,
6
's_maxage'
=> 10,
7
'public'
=> true,
8
// 'private'
=> true,
9 ));

Cache Invalidation
"There are only two hard things in Computer Science: cache invalidation and naming things." -Phil Karlton
Once an URL is cached by a gateway cache, the cache will not ask the application for that content
anymore. This allows the cache to provide fast responses and reduces the load on your application.
However, you risk delivering outdated content. A way out of this dilemma is to use long cache lifetimes,
but to actively notify the gateway cache when content changes. Reverse proxies usually provide a channel
to receive such notifications, typically through special HTTP requests.
While cache invalidation is powerful, avoid it when possible. If you fail to invalidate something,
outdated caches will be served for a potentially long time. Instead, use short cache lifetimes or
use the validation model, and adjust your controllers to perform efficient validation checks as
explained in Optimizing your Code with Validation.
Furthermore, since invalidation is a topic specific to each type of reverse proxy, using this concept
will tie you to a specific reverse proxy or need additional efforts to support different proxies.

Sometimes, however, you need that extra performance you can get when explicitly invalidating. For
invalidation, your application needs to detect when content changes and tell the cache to remove the
URLs which contain that data from its cache.
If you want to use cache invalidation, have a look at the FOSHttpCacheBundle18. This bundle
provides services to help with various cache invalidation concepts and also documents the
configuration for a couple of common caching proxies.

If one content corresponds to one URL, the PURGE model works well. You send a request to the cache
proxy with the HTTP method PURGE (using the word "PURGE" is a convention, technically this can be
any string) instead of GET and make the cache proxy detect this and remove the data from the cache
instead of going to the application to get a response.
Here is how you can configure the Symfony reverse proxy to support the PURGE HTTP method:

17. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Response.html#method_setCache
18. http://foshttpcachebundle.readthedocs.org/

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Listing 16-17

1
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5
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19
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26
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29
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31
32

// app/AppCache.php
use Symfony\Bundle\FrameworkBundle\HttpCache\HttpCache;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
// ...
class AppCache extends HttpCache
{
protected function invalidate(Request $request, $catch = false)
{
if ('PURGE' !== $request->getMethod()) {
return parent::invalidate($request, $catch);
}
if ('127.0.0.1' !== $request->getClientIp()) {
return new Response(
'Invalid HTTP method',
Response::HTTP_BAD_REQUEST
);
}
$response = new Response();
if ($this->getStore()->purge($request->getUri())) {
$response->setStatusCode(200, 'Purged');
} else {
$response->setStatusCode(404, 'Not found');
}
return $response;
}
}

You must protect the PURGE HTTP method somehow to avoid random people purging your cached
data.

Purge instructs the cache to drop a resource in all its variants (according to the Vary header, see above).
An alternative to purging is refreshing a content. Refreshing means that the caching proxy is instructed
to discard its local cache and fetch the content again. This way, the new content is already available in
the cache. The drawback of refreshing is that variants are not invalidated.
In many applications, the same content bit is used on various pages with different URLs. More flexible
concepts exist for those cases:
• Banning invalidates responses matching regular expressions on the URL or other criteria;
• Cache tagging lets you add a tag for each content used in a response so that you can invalidate
all URLs containing a certain content.

Using Edge Side Includes
Gateway caches are a great way to make your website perform better. But they have one limitation: they
can only cache whole pages. If you can't cache whole pages or if parts of a page has "more" dynamic parts,
you are out of luck. Fortunately, Symfony provides a solution for these cases, based on a technology

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called ESI19, or Edge Side Includes. Akamai wrote this specification almost 10 years ago and it allows
specific parts of a page to have a different caching strategy than the main page.
The ESI specification describes tags you can embed in your pages to communicate with the gateway
cache. Only one tag is implemented in Symfony, include, as this is the only useful one outside of Akamai
context:
Listing 16-18

1
2
3

4

5
6

7

8
9

10

11

Notice from the example that each ESI tag has a fully-qualified URL. An ESI tag represents a page
fragment that can be fetched via the given URL.

When a request is handled, the gateway cache fetches the entire page from its cache or requests it from
the backend application. If the response contains one or more ESI tags, these are processed in the same
way. In other words, the gateway cache either retrieves the included page fragment from its cache or
requests the page fragment from the backend application again. When all the ESI tags have been resolved,
the gateway cache merges each into the main page and sends the final content to the client.
All of this happens transparently at the gateway cache level (i.e. outside of your application). As you'll
see, if you choose to take advantage of ESI tags, Symfony makes the process of including them almost
effortless.

Using ESI in Symfony
First, to use ESI, be sure to enable it in your application configuration:
Listing 16-19

1 # app/config/config.yml
2 framework:
3
# ...
4
esi: { enabled: true }

Now, suppose you have a page that is relatively static, except for a news ticker at the bottom of the
content. With ESI, you can cache the news ticker independent of the rest of the page.
Listing 16-20

1
2
3
4
5
6
7
8
9

// src/AppBundle/Controller/DefaultController.php
// ...
class DefaultController extends Controller
{
public function aboutAction()
{
$response = $this->render('static/about.html.twig');
// set the shared max age - which also marks the response as public

19. http://www.w3.org/TR/esi-lang

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10
11
12
13
14 }

$response->setSharedMaxAge(600);
return $response;
}

In this example, the full-page cache has a lifetime of ten minutes. Next, include the news ticker in the
template by embedding an action. This is done via the render helper (See Embedding Controllers for
more details).
As the embedded content comes from another page (or controller for that matter), Symfony uses the
standard render helper to configure ESI tags:
Listing 16-21

1
2
3
4
5
6
7

{# app/Resources/views/static/about.html.twig #}
{# you can use a controller reference #}
{{ render_esi(controller('AppBundle:News:latest', { 'maxPerPage': 5 })) }}
{# ... or a URL #}
{{ render_esi(url('latest_news', { 'maxPerPage': 5 })) }}

By using the esi renderer (via the render_esi Twig function), you tell Symfony that the action should
be rendered as an ESI tag. You might be wondering why you would want to use a helper instead of just
writing the ESI tag yourself. That's because using a helper makes your application work even if there is
no gateway cache installed.
As you'll see below, the maxPerPage variable you pass is available as an argument to your controller
(i.e. $maxPerPage). The variables passed through render_esi also become part of the cache key so
that you have unique caches for each combination of variables and values.

When using the default render function (or setting the renderer to inline), Symfony merges the
included page content into the main one before sending the response to the client. But if you use the esi
renderer (i.e. call render_esi) and if Symfony detects that it's talking to a gateway cache that supports
ESI, it generates an ESI include tag. But if there is no gateway cache or if it does not support ESI, Symfony
will just merge the included page content within the main one as it would have done if you had used
render.
Symfony detects if a gateway cache supports ESI via another Akamai specification that is supported
out of the box by the Symfony reverse proxy.

The embedded action can now specify its own caching rules, entirely independent of the master page.
Listing 16-22

1
2
3
4
5
6
7
8
9
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11

// src/AppBundle/Controller/NewsController.php
namespace AppBundle\Controller;
// ...
class NewsController extends Controller
{
public function latestAction($maxPerPage)
{
// ...
$response->setSharedMaxAge(60);

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12
13
14 }

return $response;
}

With ESI, the full page cache will be valid for 600 seconds, but the news component cache will only last
for 60 seconds.
When using a controller reference, the ESI tag should reference the embedded action as an accessible
URL so the gateway cache can fetch it independently of the rest of the page. Symfony takes care of
generating a unique URL for any controller reference and it is able to route them properly thanks to the
FragmentListener20 that must be enabled in your configuration:
Listing 16-23

1 # app/config/config.yml
2 framework:
3
# ...
4
fragments: { path: /_fragment }

One great advantage of the ESI renderer is that you can make your application as dynamic as needed and
at the same time, hit the application as little as possible.
The listener only responds to local IP addresses or trusted proxies.

Once you start using ESI, remember to always use the s-maxage directive instead of max-age. As
the browser only ever receives the aggregated resource, it is not aware of the sub-components, and
so it will obey the max-age directive and cache the entire page. And you don't want that.

The render_esi helper supports two other useful options:
alt
Used as the alt attribute on the ESI tag, which allows you to specify an alternative URL to be used
if the src cannot be found.
ignore_errors
If set to true, an onerror attribute will be added to the ESI with a value of continue indicating that,
in the event of a failure, the gateway cache will simply remove the ESI tag silently.

Summary
Symfony was designed to follow the proven rules of the road: HTTP. Caching is no exception. Mastering
the Symfony cache system means becoming familiar with the HTTP cache models and using them
effectively. This means that, instead of relying only on Symfony documentation and code examples, you
have access to a world of knowledge related to HTTP caching and gateway caches such as Varnish.

Learn more from the Cookbook
• How to Use Varnish to Speed up my Website

20. http://api.symfony.com/3.0/Symfony/Component/HttpKernel/EventListener/FragmentListener.html

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Chapter 17

Translations
The term "internationalization" (often abbreviated i18n1) refers to the process of abstracting strings
and other locale-specific pieces out of your application into a layer where they can be translated and
converted based on the user's locale (i.e. language and country). For text, this means wrapping each with
a function capable of translating the text (or "message") into the language of the user:
Listing 17-1

1
2
3
4
5
6
7
8

// text will *always* print out in English
dump('Hello World');
die();
// text can be translated into the end-user's language or
// default to English
dump($translator->trans('Hello World'));
die();

The term locale refers roughly to the user's language and country. It can be any string that your
application uses to manage translations and other format differences (e.g. currency format). The
ISO 639-12 language code, an underscore (_), then the ISO 3166-1 alpha-23 country code (e.g.
fr_FR for French/France) is recommended.

In this chapter, you'll learn how to use the Translation component in the Symfony Framework. You can
read the Translation component documentation to learn even more. Overall, the process has several steps:
1. Enable and configure Symfony's translation service;
2. Abstract strings (i.e. "messages") by wrapping them in calls to the Translator ("Basic
Translation");
3. Create translation resources/files for each supported locale that translate each message in the
application;
4. Determine, set and manage the user's locale for the request and optionally on the user's entire
session.

1. https://en.wikipedia.org/wiki/Internationalization_and_localization
2. https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes
3. https://en.wikipedia.org/wiki/ISO_3166-1#Current_codes

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Configuration
Translations are handled by a translator service that uses the user's locale to lookup and return
translated messages. Before using it, enable the translator in your configuration:
Listing 17-2

1 # app/config/config.yml
2 framework:
3
translator: { fallbacks: [en] }

See Fallback Translation Locales for details on the fallbacks key and what Symfony does when it
doesn't find a translation.
The locale used in translations is the one stored on the request. This is typically set via a _locale attribute
on your routes (see The Locale and the URL).

Basic Translation
Translation of text is done through the translator service (Translator4). To translate a block of text
(called a message), use the trans()5 method. Suppose, for example, that you're translating a simple
message from inside a controller:
Listing 17-3

1
2
3
4
5
6
7
8
9

// ...
use Symfony\Component\HttpFoundation\Response;
public function indexAction()
{
$translated = $this->get('translator')->trans('Symfony is great');
return new Response($translated);
}

When this code is executed, Symfony will attempt to translate the message "Symfony is great" based
on the locale of the user. For this to work, you need to tell Symfony how to translate the message
via a "translation resource", which is usually a file that contains a collection of translations for a given
locale. This "dictionary" of translations can be created in several different formats, XLIFF being the
recommended format:
Listing 17-4

1
2
3
4
5
6
7
8
9
10
11
12







Symfony is great
J'aime Symfony





For information on where these files should be located, see Translation Resource/File Names and
Locations.
4. http://api.symfony.com/3.0/Symfony/Component/Translation/Translator.html
5. http://api.symfony.com/3.0/Symfony/Component/Translation/Translator.html#method_trans

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Now, if the language of the user's locale is French (e.g. fr_FR or fr_BE), the message will be translated
into J'aime Symfony. You can also translate the message inside your templates.

The Translation Process
To actually translate the message, Symfony uses a simple process:
• The locale of the current user, which is stored on the request is determined;
• A catalog (e.g. big collection) of translated messages is loaded from translation resources
defined for the locale (e.g. fr_FR). Messages from the fallback locale are also loaded and
added to the catalog if they don't already exist. The end result is a large "dictionary" of
translations.
• If the message is located in the catalog, the translation is returned. If not, the translator returns
the original message.
When using the trans() method, Symfony looks for the exact string inside the appropriate message
catalog and returns it (if it exists).

Message Placeholders
Sometimes, a message containing a variable needs to be translated:
Listing 17-5

1
2
3
4
5
6
7
8

use Symfony\Component\HttpFoundation\Response;
public function indexAction($name)
{
$translated = $this->get('translator')->trans('Hello '.$name);
return new Response($translated);
}

However, creating a translation for this string is impossible since the translator will try to look up the
exact message, including the variable portions (e.g. "Hello Ryan" or "Hello Fabien").
For details on how to handle this situation, see Message Placeholders in the components documentation.
For how to do this in templates, see Twig Templates.

Pluralization
Another complication is when you have translations that may or may not be plural, based on some
variable:
Listing 17-6

1 There is one apple.
2 There are 5 apples.

To handle this, use the transChoice()6 method or the transchoice tag/filter in your template.
For much more information, see Pluralization in the Translation component documentation.

6. http://api.symfony.com/3.0/Symfony/Component/Translation/Translator.html#method_transChoice

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Translations in Templates
Most of the time, translation occurs in templates. Symfony provides native support for both Twig and
PHP templates.

Twig Templates
Symfony provides specialized Twig tags (trans and transchoice) to help with message translation of
static blocks of text:
Listing 17-7

1 {% trans %}Hello %name%{% endtrans %}
2
3 {% transchoice count %}
4
{0} There are no apples|{1} There is one apple|]1,Inf[ There are %count% apples
5 {% endtranschoice %}

The transchoice tag automatically gets the %count% variable from the current context and passes it to
the translator. This mechanism only works when you use a placeholder following the %var% pattern.
The %var% notation of placeholders is required when translating in Twig templates using the tag.

If you need to use the percent character (%) in a string, escape it by doubling it: {% trans
%}Percent: %percent%%%{% endtrans %}

You can also specify the message domain and pass some additional variables:
Listing 17-8

1
2
3
4
5
6
7

{% trans with {'%name%': 'Fabien'} from "app" %}Hello %name%{% endtrans %}
{% trans with {'%name%': 'Fabien'} from "app" into "fr" %}Hello %name%{% endtrans %}
{% transchoice count with {'%name%': 'Fabien'} from "app" %}
{0} %name%, there are no apples|{1} %name%, there is one apple|]1,Inf[ %name%, there
are %count% apples
{% endtranschoice %}

The trans and transchoice filters can be used to translate variable texts and complex expressions:
Listing 17-9

1
2
3
4
5
6
7

{{ message|trans }}
{{ message|transchoice(5) }}
{{ message|trans({'%name%': 'Fabien'}, "app") }}
{{ message|transchoice(5, {'%name%': 'Fabien'}, 'app') }}

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Using the translation tags or filters have the same effect, but with one subtle difference: automatic
output escaping is only applied to translations using a filter. In other words, if you need to be
sure that your translated message is not output escaped, you must apply the raw filter after the
translation filter:
Listing 17-10

1
2
3
4
5
6
7
8
9
10

{# text translated between tags is never escaped #}
{% trans %}

foo


{% endtrans %}
{% set message = '

foo

' %}

{# strings and variables translated via a filter are escaped by default #}
{{ message|trans|raw }}
{{ '

bar

'|trans|raw }}

You can set the translation domain for an entire Twig template with a single tag:
Listing 17-11

1 {% trans_default_domain "app" %}

Note that this only influences the current template, not any "included" template (in order to avoid
side effects).

PHP Templates
The translator service is accessible in PHP templates through the translator helper:
Listing 17-12

1 trans('Symfony is great') ?>
2
3 transChoice(
4
'{0} There are no apples|{1} There is one apple|]1,Inf[ There are %count% apples',
5
10,
6
array('%count%' => 10)
7 ) ?>

Translation Resource/File Names and Locations
Symfony looks for message files (i.e. translations) in the following default locations:
• the app/Resources/translations directory;
• the app/Resources//translations directory;
• the Resources/translations/ directory inside of any bundle.
The locations are listed here with the highest priority first. That is, you can override the translation
messages of a bundle in any of the top 2 directories.
The override mechanism works at a key level: only the overridden keys need to be listed in a higher
priority message file. When a key is not found in a message file, the translator will automatically fall back
to the lower priority message files.
The filename of the translation files is also important: each message file must be named according to the
following path: domain.locale.loader:

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• domain: An optional way to organize messages into groups (e.g. admin, navigation or the
default messages) - see Using Message Domains;
• locale: The locale that the translations are for (e.g. en_GB, en, etc);
• loader: How Symfony should load and parse the file (e.g. xlf, php, yml, etc).
The loader can be the name of any registered loader. By default, Symfony provides many loaders,
including:
• xlf: XLIFF file;
• php: PHP file;
• yml: YAML file.
The choice of which loader to use is entirely up to you and is a matter of taste. The recommended option
is to use xlf for translations. For more options, see Loading Message Catalogs.
You can add other directories with the paths option in the configuration:
Listing 17-13

1 # app/config/config.yml
2 framework:
3
translator:
4
paths:
5
- '%kernel.root_dir%/../translations'

You can also store translations in a database, or any other storage by providing a custom class
implementing the LoaderInterface7 interface. See the translation.loader tag for more
information.

Each time you create a new translation resource (or install a bundle that includes a translation
resource), be sure to clear your cache so that Symfony can discover the new translation resources:
Listing 17-14

1 $ php bin/console cache:clear

Fallback Translation Locales
Imagine that the user's locale is fr_FR and that you're translating the key Symfony is great. To find the
French translation, Symfony actually checks translation resources for several locales:
1. First, Symfony looks for the translation in a fr_FR translation resource (e.g.
messages.fr_FR.xlf);
2. If it wasn't found, Symfony looks for the translation in a fr translation resource (e.g.
messages.fr.xlf);
3. If the translation still isn't found, Symfony uses the fallbacks configuration parameter, which
defaults to en (see Configuration).
When Symfony doesn't find a translation in the given locale, it will add the missing translation to
the log file. For details, see logging.

7. http://api.symfony.com/3.0/Symfony/Component/Translation/Loader/LoaderInterface.html

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Handling the User's Locale
The locale of the current user is stored in the request and is accessible via the request object:
Listing 17-15

1
2
3
4
5
6

use Symfony\Component\HttpFoundation\Request;
public function indexAction(Request $request)
{
$locale = $request->getLocale();
}

To set the user's locale, you may want to create a custom event listener so that it's set before any other
parts of the system (i.e. the translator) need it:
Listing 17-16

1 public function onKernelRequest(GetResponseEvent $event)
2 {
3
$request = $event->getRequest();
4
5
// some logic to determine the $locale
6
$request->setLocale($locale);
7 }

Read Making the Locale "Sticky" during a User's Session for more information on making the user's locale
"sticky" to their session.
Setting the locale using $request->setLocale() in the controller is too late to affect the translator.
Either set the locale via a listener (like above), the URL (see next) or call setLocale() directly on
the translator service.

See the The Locale and the URL section below about setting the locale via routing.

The Locale and the URL
Since you can store the locale of the user in the session, it may be tempting to use the same URL to display
a resource in different languages based on the user's locale. For example, http://www.example.com/
contact could show content in English for one user and French for another user. Unfortunately, this
violates a fundamental rule of the Web: that a particular URL returns the same resource regardless of the
user. To further muddy the problem, which version of the content would be indexed by search engines?
A better policy is to include the locale in the URL. This is fully-supported by the routing system using the
special _locale parameter:
Listing 17-17

1 # app/config/routing.yml
2 contact:
3
path:
/{_locale}/contact
4
defaults: { _controller: AppBundle:Contact:index }
5
requirements:
6
_locale: en|fr|de

When using the special _locale parameter in a route, the matched locale will automatically be set on the
Request and can be retrieved via the getLocale()8 method. In other words, if a user visits the URI /fr/
contact, the locale fr will automatically be set as the locale for the current request.
You can now use the locale to create routes to other translated pages in your application.
8. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/Request.html#method_getLocale

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Read How to Use Service Container Parameters in your Routes to learn how to avoid hardcoding
the _locale requirement in all your routes.

Setting a Default Locale
What if the user's locale hasn't been determined? You can guarantee that a locale is set on each user's
request by defining a default_locale for the framework:
Listing 17-18

1 # app/config/config.yml
2 framework:
3
default_locale: en

Translating Constraint Messages
If you're using validation constraints with the Form component, then translating the error messages is
easy: simply create a translation resource for the validators domain.
To start, suppose you've created a plain-old-PHP object that you need to use somewhere in your
application:
Listing 17-19

// src/AppBundle/Entity/Author.php
namespace AppBundle\Entity;

1
2
3
4
5
6
7

class Author
{
public $name;
}

Add constraints through any of the supported methods. Set the message option to the translation source
text. For example, to guarantee that the $name property is not empty, add the following:
Listing 17-20

1
2
3
4
5
6
7
8
9
10

// src/AppBundle/Entity/Author.php
use Symfony\Component\Validator\Constraints as Assert;
class Author
{
/**
* @Assert\NotBlank(message = "author.name.not_blank")
*/
public $name;
}

Create a translation file under the validators catalog for the constraint messages, typically in the
Resources/translations/ directory of the bundle.
Listing 17-21

1
2
3
4

5

6

7
author.name.not_blank

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8
Please enter an author name.
9

10

11

12


Translating Database Content
The translation of database content should be handled by Doctrine through the Translatable Extension9
or the Translatable Behavior10 (PHP 5.4+). For more information, see the documentation for these
libraries.

Debugging Translations
When maintaining a bundle, you may use or remove the usage of a translation message without updating
all message catalogues. The debug:translation command helps you to find these missing or unused
translation messages for a given locale. It shows you a table with the result when translating the message
in the given locale and the result when the fallback would be used. On top of that, it also shows you
when the translation is the same as the fallback translation (this could indicate that the message was not
correctly translated).
Thanks to the messages extractors, the command will detect the translation tag or filter usages in Twig
templates:
Listing 17-22

1
2
3
4
5
6
7

{% trans %}Symfony2 is great{% endtrans %}
{{ 'Symfony2 is great'|trans }}
{{ 'Symfony2 is great'|transchoice(1) }}
{% transchoice 1 %}Symfony2 is great{% endtranschoice %}

It will also detect the following translator usages in PHP templates:
Listing 17-23

1 $view['translator']->trans("Symfony2 is great");
2
3 $view['translator']->transChoice('Symfony2 is great', 1);

The extractors are not able to inspect the messages translated outside templates which means that
translator usages in form labels or inside your controllers won't be detected. Dynamic translations
involving variables or expressions are not detected in templates, which means this example won't
be analyzed:
Listing 17-24

1 {% set message = 'Symfony2 is great' %}
2 {{ message|trans }}

9. http://atlantic18.github.io/DoctrineExtensions/doc/translatable.html
10. https://github.com/KnpLabs/DoctrineBehaviors

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Suppose your application's default_locale is fr and you have configured en as the fallback locale (see
Configuration and Fallback Translation Locales for how to configure these). And suppose you've already
setup some translations for the fr locale inside an AcmeDemoBundle:
Listing 17-25

1
2
3
4
5
6
7
8
9
10
11
12







Symfony2 is great
J'aime Symfony2





and for the en locale:
Listing 17-26

1
2
3
4
5
6
7
8
9
10
11
12







Symfony2 is great
Symfony2 is great





To inspect all messages in the fr locale for the AcmeDemoBundle, run:
Listing 17-27

1 $ php bin/console debug:translation fr AcmeDemoBundle

You will get this output:

It indicates that the message Symfony2 is great is unused because it is translated, but you haven't used
it anywhere yet.
Now, if you translate the message in one of your templates, you will get this output:

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The state is empty which means the message is translated in the fr locale and used in one or more
templates.
If you delete the message Symfony2 is great from your translation file for the fr locale and run the
command, you will get:

The state indicates the message is missing because it is not translated in the fr locale but it is still used
in the template. Moreover, the message in the fr locale equals to the message in the en locale. This is a
special case because the untranslated message id equals its translation in the en locale.
If you copy the content of the translation file in the en locale, to the translation file in the fr locale and
run the command, you will get:

You can see that the translations of the message are identical in the fr and en locales which means this
message was probably copied from French to English and maybe you forgot to translate it.
By default all domains are inspected, but it is possible to specify a single domain:
Listing 17-28

1 $ php bin/console debug:translation en AcmeDemoBundle --domain=messages

When bundles have a lot of messages, it is useful to display only the unused or only the missing messages,
by using the --only-unused or --only-missing switches:
Listing 17-29

1 $ php bin/console debug:translation en AcmeDemoBundle --only-unused
2 $ php bin/console debug:translation en AcmeDemoBundle --only-missing

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Summary
With the Symfony Translation component, creating an internationalized application no longer needs to
be a painful process and boils down to just a few basic steps:
• Abstract messages in your application by wrapping each in either the trans()11 or
transChoice()12 methods (learn about this in Using the Translator);
• Translate each message into multiple locales by creating translation message files. Symfony
discovers and processes each file because its name follows a specific convention;
• Manage the user's locale, which is stored on the request, but can also be set on the user's
session.

11. http://api.symfony.com/3.0/Symfony/Component/Translation/Translator.html#method_trans
12. http://api.symfony.com/3.0/Symfony/Component/Translation/Translator.html#method_transChoice

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Chapter 18

Service Container
A modern PHP application is full of objects. One object may facilitate the delivery of email messages
while another may allow you to persist information into a database. In your application, you may create
an object that manages your product inventory, or another object that processes data from a third-party
API. The point is that a modern application does many things and is organized into many objects that
handle each task.
This chapter is about a special PHP object in Symfony that helps you instantiate, organize and retrieve
the many objects of your application. This object, called a service container, will allow you to standardize
and centralize the way objects are constructed in your application. The container makes your life easier,
is super fast, and emphasizes an architecture that promotes reusable and decoupled code. Since all core
Symfony classes use the container, you'll learn how to extend, configure and use any object in Symfony.
In large part, the service container is the biggest contributor to the speed and extensibility of Symfony.
Finally, configuring and using the service container is easy. By the end of this chapter, you'll be
comfortable creating your own objects via the container and customizing objects from any third-party
bundle. You'll begin writing code that is more reusable, testable and decoupled, simply because the
service container makes writing good code so easy.
If you want to know a lot more after reading this chapter, check out the DependencyInjection
component documentation.

What is a Service?
Put simply, a Service is any PHP object that performs some sort of "global" task. It's a purposefullygeneric name used in computer science to describe an object that's created for a specific purpose (e.g.
delivering emails). Each service is used throughout your application whenever you need the specific
functionality it provides. You don't have to do anything special to make a service: simply write a PHP
class with some code that accomplishes a specific task. Congratulations, you've just created a service!

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As a rule, a PHP object is a service if it is used globally in your application. A single Mailer service
is used globally to send email messages whereas the many Message objects that it delivers are not
services. Similarly, a Product object is not a service, but an object that persists Product objects to
a database is a service.

So what's the big deal then? The advantage of thinking about "services" is that you begin to think about
separating each piece of functionality in your application into a series of services. Since each service does
just one job, you can easily access each service and use its functionality wherever you need it. Each service
can also be more easily tested and configured since it's separated from the other functionality in your
application. This idea is called service-oriented architecture1 and is not unique to Symfony or even PHP.
Structuring your application around a set of independent service classes is a well-known and trusted
object-oriented best-practice. These skills are key to being a good developer in almost any language.

What is a Service Container?
A Service Container (or dependency injection container) is simply a PHP object that manages the
instantiation of services (i.e. objects).
For example, suppose you have a simple PHP class that delivers email messages. Without a service
container, you must manually create the object whenever you need it:
Listing 18-1

1 use AppBundle\Mailer;
2
3 $mailer = new Mailer('sendmail');
4 $mailer->send('ryan@example.com', ...);

This is easy enough. The imaginary Mailer class allows you to configure the method used to deliver the
email messages (e.g. sendmail, smtp, etc). But what if you wanted to use the mailer service somewhere
else? You certainly don't want to repeat the mailer configuration every time you need to use the Mailer
object. What if you needed to change the transport from sendmail to smtp everywhere in the
application? You'd need to hunt down every place you create a Mailer service and change it.

Creating/Configuring Services in the Container
A better answer is to let the service container create the Mailer object for you. In order for this to work,
you must teach the container how to create the Mailer service. This is done via configuration, which can
be specified in YAML, XML or PHP:
Listing 18-2

1 # app/config/services.yml
2 services:
3
app.mailer:
4
class:
AppBundle\Mailer
5
arguments:
[sendmail]

When Symfony initializes, it builds the service container using the application configuration
(app/config/config.yml by default). The exact file that's loaded is dictated by the
AppKernel::registerContainerConfiguration() method, which loads an environment-specific
configuration file (e.g. config_dev.yml for the dev environment or config_prod.yml for prod).

1. https://en.wikipedia.org/wiki/Service-oriented_architecture

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An instance of the AppBundle\Mailer class is now available via the service container. The container is
available in any traditional Symfony controller where you can access the services of the container via the
get() shortcut method:
Listing 18-3

1 class HelloController extends Controller
2 {
3
// ...
4
5
public function sendEmailAction()
6
{
7
// ...
8
$mailer = $this->get('app.mailer');
9
$mailer->send('ryan@foobar.net', ...);
10
}
11 }

When you ask for the app.mailer service from the container, the container constructs the object and
returns it. This is another major advantage of using the service container. Namely, a service is never
constructed until it's needed. If you define a service and never use it on a request, the service is never
created. This saves memory and increases the speed of your application. This also means that there's very
little or no performance hit for defining lots of services. Services that are never used are never constructed.
As a bonus, the Mailer service is only created once and the same instance is returned each time you ask
for the service. This is almost always the behavior you'll need (it's more flexible and powerful), but you'll
learn later how you can configure a service that has multiple instances in the "How to Define Non Shared
Services" cookbook article.
In this example, the controller extends Symfony's base Controller, which gives you access to the
service container itself. You can then use the get method to locate and retrieve the app.mailer
service from the service container. You can also define your controllers as services. This is a bit
more advanced and not necessary, but it allows you to inject only the services you need into your
controller.

Service Parameters
The creation of new services (i.e. objects) via the container is pretty straightforward. Parameters make
defining services more organized and flexible:
Listing 18-4

1 # app/config/services.yml
2 parameters:
3
app.mailer.transport: sendmail
4
5 services:
6
app.mailer:
7
class:
AppBundle\Mailer
8
arguments:
['%app.mailer.transport%']

The end result is exactly the same as before - the difference is only in how you defined the service. By
enclosing the app.mailer.transport string with percent (%) signs, the container knows to look for a
parameter with that name. When the container is built, it looks up the value of each parameter and uses
it in the service definition.

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If you want to use a string that starts with an @ sign as a parameter value (e.g. a very safe mailer
password) in a YAML file, you need to escape it by adding another @ sign (this only applies to the
YAML format):
Listing 18-5

1 # app/config/parameters.yml
2 parameters:
3
# This will be parsed as string '@securepass'
4
mailer_password: '@@securepass'

The percent sign inside a parameter or argument, as part of the string, must be escaped with
another percent sign:
Listing 18-6

1 http://symfony.com/?foo=%%s&bar=%%d

The purpose of parameters is to feed information into services. Of course there was nothing wrong with
defining the service without using any parameters. Parameters, however, have several advantages:
• separation and organization of all service "options" under a single parameters key;
• parameter values can be used in multiple service definitions;
• when creating a service in a bundle (this follows shortly), using parameters allows the service
to be easily customized in your application.
The choice of using or not using parameters is up to you. High-quality third-party bundles will always
use parameters as they make the service stored in the container more configurable. For the services in
your application, however, you may not need the flexibility of parameters.

Array Parameters
Parameters can also contain array values. See Array Parameters.

Importing other Container Configuration Resources
In this section, service configuration files are referred to as resources. This is to highlight the fact
that, while most configuration resources will be files (e.g. YAML, XML, PHP), Symfony is so
flexible that configuration could be loaded from anywhere (e.g. a database or even via an external
web service).

The service container is built using a single configuration resource (app/config/config.yml by default).
All other service configuration (including the core Symfony and third-party bundle configuration) must
be imported from inside this file in one way or another. This gives you absolute flexibility over the
services in your application.
External service configuration can be imported in two different ways. The first method, commonly used
to import container configuration from the bundles you've created - is via the imports directive. The
second method, although slightly more complex offers more flexibility and is commonly used to import
third-party bundle configuration. Read on to learn more about both methods.

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Importing Configuration with imports
So far, you've placed your app.mailer service container definition directly in the application
configuration file (e.g. app/config/config.yml). Of course, since the Mailer class itself lives inside the
AcmeHelloBundle, it makes more sense to put the app.mailer container definition inside the bundle as
well.
First, move the app.mailer container definition into a new container resource file inside
AcmeHelloBundle. If the Resources or Resources/config directories don't exist, create them.
Listing 18-7

1 # src/Acme/HelloBundle/Resources/config/services.yml
2 parameters:
3
app.mailer.transport: sendmail
4
5 services:
6
app.mailer:
7
class:
AppBundle\Mailer
8
arguments:
['%app.mailer.transport%']

The definition itself hasn't changed, only its location. Of course the service container doesn't know about
the new resource file. Fortunately, you can easily import the resource file using the imports key in the
application configuration.
Listing 18-8

1 # app/config/config.yml
2 imports:
3
- { resource: '@AcmeHelloBundle/Resources/config/services.yml' }

Due to the way in which parameters are resolved, you cannot use them to build paths in imports
dynamically. This means that something like the following doesn't work:
Listing 18-9

1 # app/config/config.yml
2 imports:
3
- { resource: '%kernel.root_dir%/parameters.yml' }

The imports directive allows your application to include service container configuration resources from
any other location (most commonly from bundles). The resource location, for files, is the absolute
path to the resource file. The special @AcmeHelloBundle syntax resolves the directory path of the
AcmeHelloBundle bundle. This helps you specify the path to the resource without worrying later if you
move the AcmeHelloBundle to a different directory.

Importing Configuration via Container Extensions
When developing in Symfony, you'll most commonly use the imports directive to import container
configuration from the bundles you've created specifically for your application. Third-party bundle
container configuration, including Symfony core services, are usually loaded using another method that's
more flexible and easy to configure in your application.
Here's how it works. Internally, each bundle defines its services very much like you've seen so far.
Namely, a bundle uses one or more configuration resource files (usually XML) to specify the parameters
and services for that bundle. However, instead of importing each of these resources directly from your
application configuration using the imports directive, you can simply invoke a service container extension
inside the bundle that does the work for you. A service container extension is a PHP class created by the
bundle author to accomplish two things:
• import all service container resources needed to configure the services for the bundle;
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• provide semantic, straightforward configuration so that the bundle can be configured without
interacting with the flat parameters of the bundle's service container configuration.
In other words, a service container extension configures the services for a bundle on your behalf. And as
you'll see in a moment, the extension provides a sensible, high-level interface for configuring the bundle.
Take the FrameworkBundle - the core Symfony Framework bundle - as an example. The presence of
the following code in your application configuration invokes the service container extension inside the
FrameworkBundle:
Listing 18-10

1 # app/config/config.yml
2 framework:
3
secret:
xxxxxxxxxx
4
form:
true
5
csrf_protection: true
6
router:
{ resource: '%kernel.root_dir%/config/routing.yml' }
7
# ...

When the configuration is parsed, the container looks for an extension that can handle the framework
configuration directive. The extension in question, which lives in the FrameworkBundle, is invoked and
the service configuration for the FrameworkBundle is loaded. If you remove the framework key from your
application configuration file entirely, the core Symfony services won't be loaded. The point is that you're
in control: the Symfony Framework doesn't contain any magic or perform any actions that you don't have
control over.
Of course you can do much more than simply "activate" the service container extension of the
FrameworkBundle. Each extension allows you to easily customize the bundle, without worrying about
how the internal services are defined.
In this case, the extension allows you to customize the error_handler, csrf_protection, router
configuration and much more. Internally, the FrameworkBundle uses the options specified here to define
and configure the services specific to it. The bundle takes care of creating all the necessary parameters
and services for the service container, while still allowing much of the configuration to be easily
customized. As a bonus, most service container extensions are also smart enough to perform validation notifying you of options that are missing or the wrong data type.
When installing or configuring a bundle, see the bundle's documentation for how the services for the
bundle should be installed and configured. The options available for the core bundles can be found inside
the Reference Guide.
Natively, the service container only recognizes the parameters, services, and imports directives.
Any other directives are handled by a service container extension.

If you want to expose user friendly configuration in your own bundles, read the "How to Load Service
Configuration inside a Bundle" cookbook recipe.

Referencing (Injecting) Services
So far, the original app.mailer service is simple: it takes just one argument in its constructor, which is
easily configurable. As you'll see, the real power of the container is realized when you need to create a
service that depends on one or more other services in the container.
As an example, suppose you have a new service, NewsletterManager, that helps to manage the
preparation and delivery of an email message to a collection of addresses. Of course the app.mailer
service is already really good at delivering email messages, so you'll use it inside NewsletterManager to
handle the actual delivery of the messages. This pretend class might look something like this:
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Listing 18-11

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16

// src/AppBundle/Newsletter/NewsletterManager.php
namespace AppBundle\Newsletter;
use AppBundle\Mailer;
class NewsletterManager
{
protected $mailer;
public function __construct(Mailer $mailer)
{
$this->mailer = $mailer;
}

// ...
}

Without using the service container, you can create a new NewsletterManager fairly easily from inside a
controller:
Listing 18-12

1
2
3
4
5
6
7
8
9
10

use AppBundle\Newsletter\NewsletterManager;

// ...
public function sendNewsletterAction()
{
$mailer = $this->get('app.mailer');
$newsletter = new NewsletterManager($mailer);
// ...
}

This approach is fine, but what if you decide later that the NewsletterManager class needs a second or
third constructor argument? What if you decide to refactor your code and rename the class? In both cases,
you'd need to find every place where the NewsletterManager is instantiated and modify it. Of course,
the service container gives you a much more appealing option:
Listing 18-13

1 # app/config/services.yml
2 services:
3
app.mailer:
4
# ...
5
6
app.newsletter_manager:
7
class:
AppBundle\Newsletter\NewsletterManager
8
arguments: ['@app.mailer']

In YAML, the special @app.mailer syntax tells the container to look for a service named app.mailer and
to pass that object into the constructor of NewsletterManager. In this case, however, the specified service
app.mailer must exist. If it does not, an exception will be thrown. You can mark your dependencies as
optional - this will be discussed in the next section.
Using references is a very powerful tool that allows you to create independent service classes with welldefined dependencies. In this example, the app.newsletter_manager service needs the app.mailer
service in order to function. When you define this dependency in the service container, the container
takes care of all the work of instantiating the classes.

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Using the Expression Language
The service container also supports an "expression" that allows you to inject very specific values into a
service.
For example, suppose you have a third service (not shown here), called mailer_configuration, which
has a getMailerMethod() method on it, which will return a string like sendmail based on some
configuration. Remember that the first argument to the my_mailer service is the simple string sendmail:
Listing 18-14

1 # app/config/services.yml
2 services:
3
app.mailer:
4
class:
AppBundle\Mailer
5
arguments:
[sendmail]

But instead of hardcoding this, how could we get this value from the getMailerMethod() of the new
mailer_configuration service? One way is to use an expression:
Listing 18-15

1 # app/config/config.yml
2 services:
3
my_mailer:
4
class:
Acme\HelloBundle\Mailer
5
arguments:
["@=service('mailer_configuration').getMailerMethod()"]

To learn more about the expression language syntax, see The Expression Syntax.
In this context, you have access to 2 functions:
service
Returns a given service (see the example above).
parameter
Returns a specific parameter value (syntax is just like service).
You also have access to the ContainerBuilder2 via a container variable. Here's another example:
Listing 18-16

1 services:
2
my_mailer:
3
class:
Acme\HelloBundle\Mailer
4
arguments: ["@=container.hasParameter('some_param') ? parameter('some_param') :
'default_value'"]

Expressions can be used in arguments, properties, as arguments with configurator and as arguments
to calls (method calls).

Optional Dependencies: Setter Injection
Injecting dependencies into the constructor in this manner is an excellent way of ensuring that the
dependency is available to use. If you have optional dependencies for a class, then "setter injection" may
be a better option. This means injecting the dependency using a method call rather than through the
constructor. The class would look like this:
Listing 18-17

1 namespace AppBundle\Newsletter;
2
3 use AppBundle\Mailer;

2. http://api.symfony.com/3.0/Symfony/Component/DependencyInjection/ContainerBuilder.html

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4
5 class NewsletterManager
6 {
7
protected $mailer;
8
9
public function setMailer(Mailer $mailer)
10
{
11
$this->mailer = $mailer;
12
}
13
14
// ...
15 }

Injecting the dependency by the setter method just needs a change of syntax:
Listing 18-18

1 # app/config/services.yml
2 services:
3
app.mailer:
4
# ...
5
6
app.newsletter_manager:
7
class:
AppBundle\Newsletter\NewsletterManager
8
calls:
9
- [setMailer, ['@app.mailer']]

The approaches presented in this section are called "constructor injection" and "setter injection".
The Symfony service container also supports "property injection".

Accessing the Request in a Service
Whenever you need to access the current request in a service, you can either add it as an argument to the
methods that need the request or inject the request_stack service and access the Request by calling the
getCurrentRequest()3 method:
Listing 18-19

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12
13
14
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16
17
18

namespace Acme\HelloBundle\Newsletter;
use Symfony\Component\HttpFoundation\RequestStack;
class NewsletterManager
{
protected $requestStack;
public function __construct(RequestStack $requestStack)
{
$this->requestStack = $requestStack;
}
public function anyMethod()
{
$request = $this->requestStack->getCurrentRequest();
// ... do something with the request
}

3. http://api.symfony.com/3.0/Symfony/Component/HttpFoundation/RequestStack.html#method_getCurrentRequest

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19
20
21 }

// ...

Now, just inject the request_stack, which behaves like any normal service:
Listing 18-20

1 # src/Acme/HelloBundle/Resources/config/services.yml
2 services:
3
newsletter_manager:
4
class:
Acme\HelloBundle\Newsletter\NewsletterManager
5
arguments: ["@request_stack"]

If you define a controller as a service then you can get the Request object without injecting the
container by having it passed in as an argument of your action method. See The Request object as
a Controller Argument for details.

Making References optional
Sometimes, one of your services may have an optional dependency, meaning that the dependency is not
required for your service to work properly. In the example above, the app.mailer service must exist,
otherwise an exception will be thrown. By modifying the app.newsletter_manager service definition,
you can make this reference optional. The container will then inject it if it exists and do nothing if it
doesn't:
Listing 18-21

1 # app/config/services.yml
2 services:
3
app.newsletter_manager:
4
class:
AppBundle\Newsletter\NewsletterManager
5
arguments: ['@?app.mailer']

In YAML, the special @? syntax tells the service container that the dependency is optional. Of course, the
NewsletterManager must also be rewritten to allow for an optional dependency:
Listing 18-22

1 public function __construct(Mailer $mailer = null)
2 {
3
// ...
4 }

Core Symfony and Third-Party Bundle Services
Since Symfony and all third-party bundles configure and retrieve their services via the container, you can
easily access them or even use them in your own services. To keep things simple, Symfony by default does
not require that controllers must be defined as services. Furthermore, Symfony injects the entire service
container into your controller. For example, to handle the storage of information on a user's session,
Symfony provides a session service, which you can access inside a standard controller as follows:
Listing 18-23

1 public function indexAction($bar)
2 {

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3
4
5
6
7 }

$session = $this->get('session');
$session->set('foo', $bar);

// ...

In Symfony, you'll constantly use services provided by the Symfony core or other third-party bundles
to perform tasks such as rendering templates (templating), sending emails (mailer), or accessing
information on the request through the request stack (request_stack).
You can take this a step further by using these services inside services that you've created for your
application. Beginning by modifying the NewsletterManager to use the real Symfony mailer service
(instead of the pretend app.mailer). Also pass the templating engine service to the NewsletterManager
so that it can generate the email content via a template:
Listing 18-24

1
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// src/AppBundle/Newsletter/NewsletterManager.php
namespace AppBundle\Newsletter;
use Symfony\Component\Templating\EngineInterface;
class NewsletterManager
{
protected $mailer;
protected $templating;
public function __construct(
\Swift_Mailer $mailer,
EngineInterface $templating
) {
$this->mailer = $mailer;
$this->templating = $templating;
}

// ...
}

Configuring the service container is easy:
Listing 18-25

1 # app/config/services.yml
2 services:
3
app.newsletter_manager:
4
class:
AppBundle\Newsletter\NewsletterManager
5
arguments: ['@mailer', '@templating']

The app.newsletter_manager service now has access to the core mailer and templating services. This
is a common way to create services specific to your application that leverage the power of different
services within the framework.
Be sure that the swiftmailer entry appears in your application configuration. As was mentioned
in Importing Configuration via Container Extensions, the swiftmailer key invokes the service
extension from the SwiftmailerBundle, which registers the mailer service.

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Tags
In the same way that a blog post on the Web might be tagged with things such as "Symfony" or "PHP",
services configured in your container can also be tagged. In the service container, a tag implies that the
service is meant to be used for a specific purpose. Take the following example:
Listing 18-26

1 # app/config/services.yml
2 services:
3
foo.twig.extension:
4
class: AppBundle\Extension\FooExtension
5
public: false
6
tags:
7
- { name: twig.extension }

The twig.extension tag is a special tag that the TwigBundle uses during configuration. By giving
the service this twig.extension tag, the bundle knows that the foo.twig.extension service should
be registered as a Twig extension with Twig. In other words, Twig finds all services tagged with
twig.extension and automatically registers them as extensions.
Tags, then, are a way to tell Symfony or other third-party bundles that your service should be registered
or used in some special way by the bundle.
For a list of all the tags available in the core Symfony Framework, check out The Dependency Injection
Tags. Each of these has a different effect on your service and many tags require additional arguments
(beyond just the name parameter).

Debugging Services
You can find out what services are registered with the container using the console. To show all services
and the class for each service, run:
Listing 18-27

1 $ php bin/console debug:container

By default, only public services are shown, but you can also view private services:
Listing 18-28

1 $ php bin/console debug:container --show-private

If a private service is only used as an argument to just one other service, it won't be displayed by
the debug:container command, even when using the --show-private option. See Inline Private
Services for more details.

You can get more detailed information about a particular service by specifying its id:
Listing 18-29

1 $ php bin/console debug:container app.mailer

Learn more
• Introduction to Parameters
• Compiling the Container
• Working with Container Service Definitions

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Using a Factory to Create Services
Managing Common Dependencies with Parent Services
Working with Tagged Services
How to Define Controllers as Services
How to Work with Compiler Passes in Bundles
Advanced Container Configuration

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Chapter 19

Performance
Symfony is fast, right out of the box. Of course, if you really need speed, there are many ways that you
can make Symfony even faster. In this chapter, you'll explore many of the most common and powerful
ways to make your Symfony application even faster.

Use a Byte Code Cache (e.g. APC)
One of the best (and easiest) things that you should do to improve your performance is to use a "byte
code cache". The idea of a byte code cache is to remove the need to constantly recompile the PHP source
code. There are a number of byte code caches1 available, some of which are open source. As of PHP 5.5,
PHP comes with OPcache2 built-in. For older versions, the most widely used byte code cache is probably
APC3
Using a byte code cache really has no downside, and Symfony has been architected to perform really well
in this type of environment.

Further Optimizations
Byte code caches usually monitor the source files for changes. This ensures that if the source of a
file changes, the byte code is recompiled automatically. This is really convenient, but obviously adds
overhead.
For this reason, some byte code caches offer an option to disable these checks. Obviously, when disabling
these checks, it will be up to the server admin to ensure that the cache is cleared whenever any source
files change. Otherwise, the updates you've made won't be seen.
For example, to disable these checks in APC, simply add apc.stat=0 to your php.ini configuration.

1. https://en.wikipedia.org/wiki/List_of_PHP_accelerators
2. http://php.net/manual/en/book.opcache.php
3. http://php.net/manual/en/book.apc.php

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Use Composer's Class Map Functionality
By default, the Symfony Standard Edition uses Composer's autoloader in the autoload.php4 file. This
autoloader is easy to use, as it will automatically find any new classes that you've placed in the registered
directories.
Unfortunately, this comes at a cost, as the loader iterates over all configured namespaces to find a
particular file, making file_exists calls until it finally finds the file it's looking for.
The simplest solution is to tell Composer to build a "class map" (i.e. a big array of the locations of all the
classes). This can be done from the command line, and might become part of your deploy process:
Listing 19-1

1 $ composer dump-autoload --optimize

Internally, this builds the big class map array in vendor/composer/autoload_classmap.php.

Caching the Autoloader with APC
Another solution is to cache the location of each class after it's located the first time. Symfony comes with
a class - ApcClassLoader5 - that does exactly this. To use it, just adapt your front controller file. If you're
using the Standard Distribution, this code should already be available as comments in this file:
Listing 19-2

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// app.php
// ...
$loader = require __DIR__.'/../app/autoload.php';
include_once __DIR__.'/../var/bootstrap.php.cache';
// Enable APC for autoloading to improve performance.
// You should change the ApcClassLoader first argument to a unique prefix
// in order to prevent cache key conflicts with other applications
// also using APC.
/*
$apcLoader = new Symfony\Component\ClassLoader\ApcClassLoader(sha1(__FILE__), $loader);
$loader->unregister();
$apcLoader->register(true);
*/
// ...

For more details, see Cache a Class Loader.
When using the APC autoloader, if you add new classes, they will be found automatically and
everything will work the same as before (i.e. no reason to "clear" the cache). However, if you
change the location of a particular namespace or prefix, you'll need to flush your APC cache.
Otherwise, the autoloader will still be looking at the old location for all classes inside that
namespace.

4. https://github.com/symfony/symfony-standard/blob/master/app/autoload.php
5. http://api.symfony.com/3.0/Symfony/Component/ClassLoader/ApcClassLoader.html

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Use Bootstrap Files
To ensure optimal flexibility and code reuse, Symfony applications leverage a variety of classes and 3rd
party components. But loading all of these classes from separate files on each request can result in some
overhead. To reduce this overhead, the Symfony Standard Edition provides a script to generate a socalled bootstrap file6, consisting of multiple classes definitions in a single file. By including this file (which
contains a copy of many of the core classes), Symfony no longer needs to include any of the source files
containing those classes. This will reduce disc IO quite a bit.
If you're using the Symfony Standard Edition, then you're probably already using the bootstrap file. To be
sure, open your front controller (usually app.php) and check to make sure that the following line exists:
Listing 19-3

1 include_once __DIR__.'/../var/bootstrap.php.cache';

Note that there are two disadvantages when using a bootstrap file:
• the file needs to be regenerated whenever any of the original sources change (i.e. when you
update the Symfony source or vendor libraries);
• when debugging, one will need to place break points inside the bootstrap file.
If you're using the Symfony Standard Edition, the bootstrap file is automatically rebuilt after updating the
vendor libraries via the composer install command.

Bootstrap Files and Byte Code Caches
Even when using a byte code cache, performance will improve when using a bootstrap file since there
will be fewer files to monitor for changes. Of course if this feature is disabled in the byte code cache (e.g.
apc.stat=0 in APC), there is no longer a reason to use a bootstrap file.

6. https://github.com/sensiolabs/SensioDistributionBundle/blob/master/Composer/ScriptHandler.php

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