.. index:: single: Controller
A controller is a PHP function you create that reads information from the
Request object and creates and returns a Response object. The response could
be an HTML page, JSON, XML, a file download, a redirect, a 404 error or anything
else. The controller executes whatever arbitrary logic your application needs
to render the content of a page.
Tip
If you haven't already created your first working page, check out :doc:`/page_creation` and then come back!
.. index:: single: Controller; Simple example
While a controller can be any PHP callable (function, method on an object,
or a Closure), a controller is usually a method inside a controller
class:
// src/Controller/LuckyController.php
namespace App\Controller;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;
class LuckyController
{
/**
* @Route("/lucky/number/{max}", name="app_lucky_number")
*/
public function number($max)
{
$number = random_int(0, $max);
return new Response(
'<html><body>Lucky number: '.$number.'</body></html>'
);
}
}
The controller is the number() method, which lives inside the
controller class LuckyController.
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
usekeyword imports theResponseclass, which the controller must return. - line 7: The class can technically be called anything, but it's suffixed
with
Controllerby convention. - line 12: The action method is allowed to have a
$maxargument thanks to the{max}:doc:`wildcard in the route </routing>`. - line 16: The controller creates and returns a
Responseobject.
.. index:: single: Controller; Routes and controllers
In order to view the result of this controller, you need to map a URL to it via
a route. This was done above with the @Route("/lucky/number/{max}")
:ref:`route annotation <annotation-routes>`.
To see your page, go to this URL in your browser: http://localhost:8000/lucky/number/100
For more information on routing, see :doc:`/routing`.
.. index:: single: Controller; Base controller class
To aid development, Symfony comes with an optional base controller class called :class:`Symfony\\Bundle\\FrameworkBundle\\Controller\\AbstractController`. It can be extended to gain access to helper methods.
Add the use statement atop your controller class and then modify
LuckyController to extend it:
// src/Controller/LuckyController.php
namespace App\Controller;
+ use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
- class LuckyController
+ class LuckyController extends AbstractController
{
// ...
}That's it! You now have access to methods like :ref:`$this->render() <controller-rendering-templates>` and many others that you'll learn about next.
.. index:: single: Controller; Redirecting
The :method:`Symfony\\Bundle\\FrameworkBundle\\Controller\\AbstractController::generateUrl` method is just a helper method that generates the URL for a given route:
$url = $this->generateUrl('app_lucky_number', ['max' => 10]);
If you want to redirect the user to another page, use the redirectToRoute()
and redirect() methods:
use Symfony\Component\HttpFoundation\RedirectResponse;
// ...
public function index()
{
// redirects to the "homepage" route
return $this->redirectToRoute('homepage');
// redirectToRoute is a shortcut for:
// return new RedirectResponse($this->generateUrl('homepage'));
// does a permanent - 301 redirect
return $this->redirectToRoute('homepage', [], 301);
// redirect to a route with parameters
return $this->redirectToRoute('app_lucky_number', ['max' => 10]);
// redirects to a route and maintains the original query string parameters
return $this->redirectToRoute('blog_show', $request->query->all());
// redirects externally
return $this->redirect('http://symfony.com/doc');
}
Caution!
The redirect() method does not check its destination in any way. If you
redirect to a URL provided by end-users, your application may be open
to the unvalidated redirects security vulnerability.
.. index:: single: Controller; 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:
// renders templates/lucky/number.html.twig
return $this->render('lucky/number.html.twig', ['number' => $number]);
Templating and Twig are explained more in the :doc:`Creating and Using Templates article </templates>`.
.. index:: single: Controller; Accessing services
Symfony comes packed with a lot of useful classes and functionalities, called :doc:`services </service_container>`. These are used for rendering templates, sending emails, querying the database and any other "work" you can think of.
If you need a service in a controller, type-hint an argument with its class (or interface) name. Symfony will automatically pass you the service you need:
use Psr\Log\LoggerInterface;
// ...
/**
* @Route("/lucky/number/{max}")
*/
public function number($max, LoggerInterface $logger)
{
$logger->info('We are logging!');
// ...
}
Awesome!
What other services can you type-hint? To see them, use the debug:autowiring console
command:
$ php bin/console debug:autowiring
If you need control over the exact value of an argument, you can :ref:`bind <services-binding>` the argument by its name:
.. configuration-block::
.. code-block:: yaml
# config/services.yaml
services:
# ...
# explicitly configure the service
App\Controller\LuckyController:
tags: [controller.service_arguments]
bind:
# for any $logger argument, pass this specific service
$logger: '@monolog.logger.doctrine'
# for any $projectDir argument, pass this parameter value
$projectDir: '%kernel.project_dir%'
.. code-block:: xml
<!-- config/services.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
https://symfony.com/schema/dic/services/services-1.0.xsd">
<services>
<!-- ... -->
<!-- Explicitly configure the service -->
<service id="App\Controller\LuckyController">
<tag name"controller.service_arguments"/>
<bind key="$logger"
type="service"
id="monolog.logger.doctrine"
/>
<bind key="$projectDir">%kernel.project_dir%</bind>
</service>
</services>
</container>
.. code-block:: php
// config/services.php
use App\Controller\LuckyController;
use Symfony\Component\DependencyInjection\Reference;
$container->register(LuckyController::class)
->addTag('controller.service_arguments')
->setBindings([
'$logger' => new Reference('monolog.logger.doctrine'),
'$projectDir' => '%kernel.project_dir%'
])
;
Like with all services, you can also use regular :ref:`constructor injection <services-constructor-injection>` in your controllers.
For more information about services, see the :doc:`/service_container` article.
To save time, you can install Symfony Maker and tell Symfony to generate a new controller class:
$ php bin/console make:controller BrandNewController
created: src/Controller/BrandNewController.php
created: templates/brandnew/index.html.twig
If you want to generate an entire CRUD from a Doctrine :doc:`entity </doctrine>`, use:
$ php bin/console make:crud Product
created: src/Controller/ProductController.php
created: src/Form/ProductType.php
created: templates/product/_delete_form.html.twig
created: templates/product/_form.html.twig
created: templates/product/edit.html.twig
created: templates/product/index.html.twig
created: templates/product/new.html.twig
created: templates/product/show.html.twig
.. versionadded:: 1.2
The ``make:crud`` command was introduced in MakerBundle 1.2.
.. index:: single: Controller; Managing errors single: Controller; 404 pages
When things are not found, you should return a 404 response. To do this, throw a special type of exception:
use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
// ...
public function index()
{
// retrieve the object from database
$product = ...;
if (!$product) {
throw $this->createNotFoundException('The product does not exist');
// the above is just a shortcut for:
// throw new NotFoundHttpException('The product does not exist');
}
return $this->render(...);
}
The :method:`Symfony\\Bundle\\FrameworkBundle\\Controller\\AbstractController::createNotFoundException` method is just a shortcut to create a special :class:`Symfony\\Component\\HttpKernel\\Exception\\NotFoundHttpException` object, which ultimately triggers a 404 HTTP response inside Symfony.
If you throw an exception that extends or is an instance of :class:`Symfony\\Component\\HttpKernel\\Exception\\HttpException`, Symfony will use the appropriate HTTP status code. Otherwise, the response will have a 500 HTTP status code:
// this exception ultimately generates a 500 status error
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 in "Debug" mode - see :ref:`page-creation-environments`).
To customize the error page that's shown to the user, see the :doc:`/controller/error_pages` article.
What if you need to read query parameters, grab a request header or get access
to an uploaded file? That information is stored in Symfony's Request
object. To access it in your controller, add it as an argument and
type-hint it with the Request class:
use Symfony\Component\HttpFoundation\Request;
public function index(Request $request, $firstName, $lastName)
{
$page = $request->query->get('page', 1);
// ...
}
:ref:`Keep reading <request-object-info>` for more information about using the Request object.
.. index:: single: Controller; The session single: Session
Symfony provides a session service that you can use to store information about the user between requests. Session is enabled by default, but will only be started if you read or write from it.
Session storage and other configuration can be controlled under the
:ref:`framework.session configuration <config-framework-session>` in
config/packages/framework.yaml.
To get the session, add an argument and type-hint it with :class:`Symfony\\Component\\HttpFoundation\\Session\\SessionInterface`:
use Symfony\Component\HttpFoundation\Session\SessionInterface;
public function index(SessionInterface $session)
{
// stores an attribute for reuse during a later user request
$session->set('foo', 'bar');
// gets the attribute set by another controller in another request
$foobar = $session->get('foobar');
// uses a default value if the attribute doesn't exist
$filters = $session->get('filters', []);
}
Stored attributes remain in the session for the remainder of that user's session.
For more info, see :doc:`/session`.
.. index:: single: 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 :doc:`form </forms>` submission:
use Symfony\Component\HttpFoundation\Request;
public function update(Request $request)
{
// ...
if ($form->isSubmitted() && $form->isValid()) {
// do some sort of processing
$this->addFlash(
'notice',
'Your changes were saved!'
);
// $this->addFlash() is equivalent to $request->getSession()->getFlashBag()->add()
return $this->redirectToRoute(...);
}
return $this->render(...);
}
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 using the flashes() method provided
by the :ref:`Twig global app variable <twig-app-variable>`:
{# templates/base.html.twig #}
{# read and display just one flash message type #}
{% for message in app.flashes('notice') %}
<div class="flash-notice">
{{ message }}
</div>
{% endfor %}
{# read and display several types of flash messages #}
{% for label, messages in app.flashes(['success', 'warning']) %}
{% for message in messages %}
<div class="flash-{{ label }}">
{{ message }}
</div>
{% endfor %}
{% endfor %}
{# read and display all flash messages #}
{% for label, messages in app.flashes %}
{% for message in messages %}
<div class="flash-{{ label }}">
{{ message }}
</div>
{% endfor %}
{% 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.
Tip
You can use the :method:`Symfony\\Component\\HttpFoundation\\Session\\Flash\\FlashBagInterface::peek` method instead to retrieve the message while keeping it in the bag.
.. index:: single: Controller; Response object
As mentioned :ref:`earlier <controller-request-argument>`, Symfony will
pass the Request object to any controller argument that is type-hinted with
the Request class:
use Symfony\Component\HttpFoundation\Request;
public function index(Request $request)
{
$request->isXmlHttpRequest(); // is it an Ajax request?
$request->getPreferredLanguage(['en', 'fr']);
// retrieves GET and POST variables respectively
$request->query->get('page');
$request->request->get('page');
// retrieves SERVER variables
$request->server->get('HTTP_HOST');
// retrieves an instance of UploadedFile identified by foo
$request->files->get('foo');
// retrieves a COOKIE value
$request->cookies->get('PHPSESSID');
// retrieves 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 a public headers property.
This object is of the type :class:`Symfony\\Component\\HttpFoundation\\ResponseHeaderBag`
and provides methods for getting and setting response headers. The header names are
normalized. As a result, the name Content-Type is equivalent to
the name content-type or content_type.
In Symfony, a controller is required to return a Response object:
use Symfony\Component\HttpFoundation\Response;
// creates a simple Response with a 200 status code (the default)
$response = new Response('Hello '.$name, Response::HTTP_OK);
// creates a CSS-response with a 200 status code
$response = new Response('<style> ... </style>');
$response->headers->set('Content-Type', 'text/css');
To facilitate this, different response objects are included to address different
response types. Some of these are mentioned below. To learn more about the
Request and Response (and different Response classes), see the
:ref:`HttpFoundation component documentation <component-http-foundation-request>`.
To get the value of any :ref:`configuration parameter <configuration-parameters>`
from a controller, use the getParameter() helper method:
// ...
public function index()
{
$contentsDir = $this->getParameter('kernel.project_dir').'/contents';
// ...
}
To return JSON from a controller, use the json() helper method. This returns a
JsonResponse object that encodes the data automatically:
// ...
public function index()
{
// returns '{"username":"jane.doe"}' and sets the proper Content-Type header
return $this->json(['username' => 'jane.doe']);
// the shortcut defines three optional arguments
// return $this->json($data, $status = 200, $headers = [], $context = []);
}
If the :doc:`serializer service </serializer>` is enabled in your application, it will be used to serialize the data to JSON. Otherwise, the :phpfunction:`json_encode` function is used.
You can use the :method:`Symfony\\Bundle\\FrameworkBundle\\Controller\\AbstractController::file` helper to serve a file from inside a controller:
public function download()
{
// send the file contents and force the browser to download it
return $this->file('/path/to/some_file.pdf');
}
The file() helper provides some arguments to configure its behavior:
use Symfony\Component\HttpFoundation\File\File;
use Symfony\Component\HttpFoundation\ResponseHeaderBag;
public function download()
{
// load the file from the filesystem
$file = new File('/path/to/some_file.pdf');
return $this->file($file);
// rename the downloaded file
return $this->file($file, 'custom_name.pdf');
// display the file contents in the browser instead of downloading it
return $this->file('invoice_3241.pdf', 'my_invoice.pdf', ResponseHeaderBag::DISPOSITION_INLINE);
}
In Symfony, a controller is usually a class method which is used to accept
requests, and return a Response object. When mapped with a URL, a controller
becomes accessible and its response can be viewed.
To facilitate the development of controllers, Symfony provides an
AbstractController. It can be used to extend the controller class allowing
access to some frequently used utilities such as render() and
redirectToRoute(). The AbstractController also provides the
createNotFoundException() utility which is used to return a page not found
response.
In other articles, you'll learn how to use specific services from inside your controller that will help you persist and fetch objects from a database, process form submissions, handle caching and more.
Next, learn all about :doc:`rendering templates with Twig </templates>`.
.. toctree::
:hidden:
templates
.. toctree::
:maxdepth: 1
:glob:
controller/*