Controller
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Read the updated version of this page for Symfony 7.1 (the current stable version).
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 runs 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 Create your First Page in Symfony and then come back!
A Basic Controller
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:
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// 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(int $max): Response
{
$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
use
keyword imports theResponse
class, which the controller must return. - line 7: The class can technically be called anything, but it's suffixed
with
Controller
by convention. - line 10: The action method is allowed to have a
$max
argument thanks to the{max}
wildcard in the route. - line 14: The controller creates and returns a
Response
object.
Mapping a URL to a Controller
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}')]
route attribute.
To see your page, go to this URL in your browser: http://localhost:8000/lucky/number/100
For more information on routing, see Routing.
The Base Controller Class & Services
To aid development, Symfony comes with an optional base controller class called 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:
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// 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 $this->render() and many others that you'll learn about next.
Generating URLs
The generateUrl() method is just a helper method that generates the URL for a given route:
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$url = $this->generateUrl('app_lucky_number', ['max' => 10]);
Redirecting
If you want to redirect the user to another page, use the redirectToRoute()
and redirect()
methods:
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use Symfony\Component\HttpFoundation\RedirectResponse;
use Symfony\Component\HttpFoundation\Response;
// ...
public function index(): RedirectResponse
{
// redirects to the "homepage" route
return $this->redirectToRoute('homepage');
// redirectToRoute is a shortcut for:
// return new RedirectResponse($this->generateUrl('homepage'));
// does a permanent HTTP 301 redirect
return $this->redirectToRoute('homepage', [], 301);
// if you prefer, you can use PHP constants instead of hardcoded numbers
return $this->redirectToRoute('homepage', [], Response::HTTP_MOVED_PERMANENTLY);
// 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 to the current route (e.g. for Post/Redirect/Get pattern):
return $this->redirectToRoute($request->attributes->get('_route'));
// redirects externally
return $this->redirect('http://symfony.com/doc');
}
Danger
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.
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:
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// renders templates/lucky/number.html.twig
return $this->render('lucky/number.html.twig', ['number' => $number]);
Templating and Twig are explained more in the Creating and Using Templates article.
Fetching Services
Symfony comes packed with a lot of useful classes and functionalities, called services. 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:
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use Psr\Log\LoggerInterface;
use Symfony\Component\HttpFoundation\Response;
// ...
#[Route('/lucky/number/{max}')]
public function number(int $max, LoggerInterface $logger): Response
{
$logger->info('We are logging!');
// ...
}
Awesome!
What other services can you type-hint? To see them, use the debug:autowiring
console
command:
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$ php bin/console debug:autowiring
Tip
If you need control over the exact value of an argument, or require a parameter,
you can use the #[Autowire]
attribute:
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// ...
use Psr\Log\LoggerInterface;
use Symfony\Component\DependencyInjection\Attribute\Autowire;
use Symfony\Component\HttpFoundation\Response;
class LuckyController extends AbstractController
{
public function number(
int $max,
// inject a specific logger service
#[Autowire(service: 'monolog.logger.request')]
LoggerInterface $logger,
// or inject parameter values
#[Autowire('%kernel.project_dir%')]
string $projectDir
): Response
{
$logger->info('We are logging!');
// ...
}
}
You can read more about this attribute in Defining Services Dependencies Automatically (Autowiring).
6.1
The #[Autowire]
attribute was introduced in Symfony 6.1.
Like with all services, you can also use regular constructor injection in your controllers.
For more information about services, see the Service Container article.
Generating Controllers
To save time, you can install Symfony Maker and tell Symfony to generate a new controller class:
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$ 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 entity, use:
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$ 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
Managing Errors and 404 Pages
When things are not found, you should return a 404 response. To do this, throw a special type of exception:
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use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
// ...
public function index(): Response
{
// 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 createNotFoundException() method is just a shortcut to create a special NotFoundHttpException object, which ultimately triggers a 404 HTTP response inside Symfony.
If you throw an exception that extends or is an instance of HttpException, Symfony will use the appropriate HTTP status code. Otherwise, the response will have a 500 HTTP status code:
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// 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 Configuring Symfony).
To customize the error page that's shown to the user, see the How to Customize Error Pages article.
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? 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:
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use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
// ...
public function index(Request $request): Response
{
$page = $request->query->get('page', 1);
// ...
}
Keep reading for more information about using the Request object.
Automatic Mapping Of The Request
It is possible to automatically map request's payload and/or query parameters to your controller's action arguments with attributes.
Mapping Query Parameters Individually
Let's say a user sends you a request with the following query string:
https://example.com/dashboard?firstName=John&lastName=Smith&age=27
.
Thanks to the MapQueryParameter
attribute, arguments of your controller's action can be automatically fulfilled:
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use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Attribute\MapQueryParameter;
// ...
public function dashboard(
#[MapQueryParameter] string $firstName,
#[MapQueryParameter] string $lastName,
#[MapQueryParameter] int $age,
): Response
{
// ...
}
#[MapQueryParameter]
can take an optional argument called filter
. You can use the
Validate Filters constants defined in PHP:
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use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Attribute\MapQueryParameter;
// ...
public function dashboard(
#[MapQueryParameter(filter: \FILTER_VALIDATE_REGEXP, options: ['regexp' => '/^\w++$/'])] string $firstName,
#[MapQueryParameter] string $lastName,
#[MapQueryParameter(filter: \FILTER_VALIDATE_INT)] int $age,
): Response
{
// ...
}
6.3
The MapQueryParameter attribute was introduced in Symfony 6.3.
Mapping The Whole Query String
Another possibility is to map the entire query string into an object that will hold available query parameters. Let's say you declare the following DTO with its optional validation constraints:
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namespace App\Model;
use Symfony\Component\Validator\Constraints as Assert;
class UserDTO
{
public function __construct(
#[Assert\NotBlank]
public string $firstName,
#[Assert\NotBlank]
public string $lastName,
#[Assert\GreaterThan(18)]
public int $age,
) {
}
}
You can then use the MapQueryString attribute in your controller:
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use App\Model\UserDto;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Attribute\MapQueryString;
// ...
public function dashboard(
#[MapQueryString] UserDTO $userDto
): Response
{
// ...
}
You can customize the validation groups used during the mapping thanks to the
validationGroups
option:
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public function dashboard(
#[MapQueryString(validationGroups: ['strict', 'edit'])] UserDTO $userDto
): Response
{
// ...
}
6.3
The MapQueryString attribute was introduced in Symfony 6.3.
Mapping Request Payload
When creating an API and dealing with other HTTP methods than GET
(like
POST
or PUT
), user's data are not stored in the query string
but directly in the request payload, like this:
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{
"firstName": "John",
"lastName": "Smith",
"age": 28
}
In this case, it is also possible to directly map this payload to your DTO by using the MapRequestPayload attribute:
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use App\Model\UserDto;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Attribute\MapRequestPayload;
// ...
public function dashboard(
#[MapRequestPayload] UserDTO $userDto
): Response
{
// ...
}
This attribute allows you to customize the serialization context as well as the class responsible of doing the mapping between the request and your DTO:
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public function dashboard(
#[MapRequestPayload(
serializationContext: ['...'],
resolver: App\Resolver\UserDtoResolver
)]
UserDTO $userDto
): Response
{
// ...
}
You can also customize the validation groups used as well as supported payload formats:
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public function dashboard(
#[MapRequestPayload(acceptFormat: 'json', validationGroups: ['strict', 'read'])] UserDTO $userDto
): Response
{
// ...
}
Tip
If you build a JSON API, make sure to declare your route as using the JSON format. This will make the error handling output a JSON response in case of validation errors, rather than an HTML page:
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#[Route('/dashboard', name: 'dashboard', format: 'json')]
Make sure to install phpstan/phpdoc-parser and phpdocumentor/type-resolver if you want to map a nested array of specific DTOs:
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public function dashboard(
#[MapRequestPayload()] EmployeesDTO $employeesDto
): Response
{
// ...
}
final class EmployeesDTO
{
/**
* @param UserDTO[] $users
*/
public function __construct(
public readonly array $users = []
) {}
}
6.3
The MapRequestPayload attribute was introduced in Symfony 6.3.
Managing the Session
You can 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:
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use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
// ...
public function update(Request $request): Response
{
// ...
if ($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(/* ... */);
}
Reading for more information about using Sessions.
The Request and Response Object
As mentioned earlier, Symfony will
pass the Request
object to any controller argument that is type-hinted with
the Request
class:
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use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
public function index(Request $request): Response
{
$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 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:
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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
HttpFoundation component documentation.
Accessing Configuration Values
To get the value of any configuration parameter
from a controller, use the getParameter()
helper method:
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// ...
public function index(): Response
{
$contentsDir = $this->getParameter('kernel.project_dir').'/contents';
// ...
}
Returning JSON Response
To return JSON from a controller, use the json()
helper method. This returns a
JsonResponse
object that encodes the data automatically:
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use Symfony\Component\HttpFoundation\JsonResponse;
// ...
public function index(): JsonResponse
{
// 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 serializer service is enabled in your application, it will be used to serialize the data to JSON. Otherwise, the json_encode function is used.
Streaming File Responses
You can use the file() helper to serve a file from inside a controller:
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use Symfony\Component\HttpFoundation\BinaryFileResponse;
// ...
public function download(): BinaryFileResponse
{
// 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:
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use Symfony\Component\HttpFoundation\File\File;
use Symfony\Component\HttpFoundation\ResponseHeaderBag;
// ...
public function download(): BinaryFileResponse
{
// 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);
}
Sending Early Hints
6.3
The Early Hints helper of the AbstractController
was introduced
in Symfony 6.3.
Early hints tell the browser to start downloading some assets even before the application sends the response content. This improves perceived performance because the browser can prefetch resources that will be needed once the full response is finally sent. These resources are commonly Javascript or CSS files, but they can be any type of resource.
Note
In order to work, the SAPI you're using must support this feature, like FrankenPHP.
You can send early hints from your controller action thanks to the sendEarlyHints() method:
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namespace App\Controller;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;
use Symfony\Component\WebLink\Link;
class HomepageController extends AbstractController
{
#[Route("/", name: "homepage")]
public function index(): Response
{
$response = $this->sendEarlyHints([
new Link(rel: 'preconnect', href: 'https://fonts.google.com'),
(new Link(href: '/style.css'))->withAttribute('as', 'stylesheet'),
(new Link(href: '/script.js'))->withAttribute('as', 'script'),
]);
// prepare the contents of the response...
return $this->render('homepage/index.html.twig', response: $response);
}
}
Technically, Early Hints are an informational HTTP response with the status code
103
. The sendEarlyHints()
method creates a Response
object with that
status code and sends its headers immediately.
This way, browsers can start downloading the assets immediately; like the
style.css
and script.js
files in the above example. The
sendEarlyHints()
method also returns the Response
object, which you
must use to create the full response sent from the controller action.
Final Thoughts
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.
Keep Going!
Next, learn all about rendering templates with Twig.