How to Define Controllers as Services

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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']

Note

If you don't use either autowiring or autoconfiguration and you extend the AbstractController, you'll need to apply other tags and make some method calls to register your controllers as services:

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# config/services.yaml

# this extended configuration is only required when not using autowiring/autoconfiguration,
# which is uncommon and not recommended

abstract_controller.locator:
    class: Symfony\Component\DependencyInjection\ServiceLocator
    arguments:
        -
            router: '@router'
            request_stack: '@request_stack'
            http_kernel: '@http_kernel'
            session: '@session'
            parameter_bag: '@parameter_bag'
            # you can add more services here as you need them (e.g. the `serializer`
            # service) and have a look at the AbstractController class to see
            # which services are defined in the locator

App\Controller\:
    resource: '../src/Controller/'
    tags: ['controller.service_arguments']
    calls:
        - [setContainer, ['@abstract_controller.locator']]

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

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

5.3

The #[AsController] attribute was introduced in Symfony 5.3.

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(): Response
    {
        // ...
    }
}

Invokable Controllers

Controllers can also define a single action using the __invoke() method, which is a common practice when following the ADR pattern (Action-Domain-Responder):

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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(string $name = 'World'): Response
    {
        return new Response(sprintf('Hello %s!', $name));
    }
}

Alternatives to base Controller Methods

When using a controller defined as a service, you can still extend the AbstractController base controller and use its shortcuts. But, you don't need to! You can choose to extend nothing, and use dependency injection to access different services.

The base Controller class source code is a great way to see how to accomplish common tasks. For example, $this->render() is usually used to render a Twig template and return a Response. But, you can also do this directly:

In a controller that's defined as a service, you can instead inject the twig service and use it directly:

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

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

class HelloController
{
    private Environment $twig;

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

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

        return new Response($content);
    }
}

You can also use a special action-based dependency injection to receive services as arguments to your controller action methods.

Base Controller Methods and Their Service Replacements

The best way to see how to replace base Controller convenience methods is to look at the AbstractController class that holds its logic.

If you want to know what type-hints to use for each service, see the getSubscribedServices() method in AbstractController.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.
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