How to Define Controllers as Services

In Symfony, a controller does not need to be registered as a service. But if you're using the default services.yaml configuration, and your controllers extend the AbstractController class, they are automatically registered as services. This means you can use dependency injection like any other normal service.

If your controllers don't extend the AbstractController class, you must explicitly mark your controller services as public. Alternatively, you can apply the controller.service_arguments tag to your controller services. This will make the tagged services public and will allow you to inject services in method parameters:

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# config/services.yaml

# controllers are imported separately to make sure services can be injected
# as action arguments even if you don't extend any base controller class
App\Controller\:
   resource: '../src/Controller/'
   tags: ['controller.service_arguments']

If you prefer, you can use the #[AsController] PHP attribute to automatically apply the controller.service_arguments tag to your controller services:

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// src/Controller/HelloController.php
namespace App\Controller;

use Symfony\Component\HttpKernel\Attribute\AsController;
use Symfony\Component\Routing\Annotation\Route;

#[AsController]
class HelloController
{
    #[Route('/hello', name: 'hello', methods: ['GET'])]
    public function index()
    {
        // ...
    }
}

Registering your controller as a service is the first step, but you also need to update your routing config to reference the service properly, so that Symfony knows to use it.

Use the service_id::method_name syntax to refer to the controller method. If the service id is the fully-qualified class name (FQCN) of your controller, as Symfony recommends, then the syntax is the same as if the controller was not a service like: App\Controller\HelloController::index:

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// src/Controller/HelloController.php
namespace App\Controller;

use Symfony\Component\Routing\Annotation\Route;

class HelloController
{
    #[Route('/hello', name: 'hello', methods: ['GET'])]
    public function index()
    {
        // ...
    }
}

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# config/routes.yaml
hello:
    path:       /hello
    controller: App\Controller\HelloController::index
    methods:    GET

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<!-- config/routes.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<routes xmlns="http://symfony.com/schema/routing"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/routing
        https://symfony.com/schema/routing/routing-1.0.xsd">

    <route id="hello" path="/hello" controller="App\Controller\HelloController::index" methods="GET"/>

</routes>

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// config/routes.php
use App\Controller\HelloController;
use Symfony\Component\Routing\Loader\Configurator\RoutingConfigurator;

return function (RoutingConfigurator $routes) {
    $routes->add('hello', '/hello')
        ->controller([HelloController::class, 'index'])
        ->methods(['GET'])
    ;
};

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// src/Controller/Hello.php
namespace App\Controller;

use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;

#[Route('/hello/{name}', name: 'hello')]
class Hello
{
    public function __invoke($name = 'World')
    {
        return new Response(sprintf('Hello %s!', $name));
    }
}

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# config/routes.yaml
hello:
    path:       /hello/{name}
    controller: App\Controller\HelloController

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<!-- config/routes.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<routes xmlns="http://symfony.com/schema/routing"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/routing
        https://symfony.com/schema/routing/routing-1.0.xsd">

    <route id="hello" path="/hello/{name}">
        <default key="_controller">App\Controller\HelloController</default>
    </route>

</routes>

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use App\Controller\HelloController;

// app/config/routing.php
$collection->add('hello', new Route('/hello', [
    '_controller' => HelloController::class,
]));

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// src/Controller/HelloController.php
namespace App\Controller;

use Symfony\Component\HttpFoundation\Response;
use Twig\Environment;

class HelloController
{
    private $twig;

    public function __construct(Environment $twig)
    {
        $this->twig = $twig;
    }

    public function index($name)
    {
        $content = $this->twig->render(
            'hello/index.html.twig',
            ['name' => $name]
        );

        return new Response($content);
    }
}