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, your controllers are already registered as services. This means you can use dependency injection like any other normal service.
Referencing your Service from Routing
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()
{
// ...
}
}
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($name = 'World')
{
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 $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);
}
}
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 ControllerTrait that holds its logic.
If you want to know what type-hints to use for each service, see the
getSubscribedServices()
method in AbstractController.