How to Define Controllers as Services

Referencing your Service from Routing

Registering your controller as a service is great, but you also need to make sure that your routing references the service properly, so that Symfony knows to use it.

If the service id is the fully-qualified class name (FQCN) of your controller, you're done! You can use the normal AppBundle:Hello:index syntax in your routing and it will find your service.

But, if your service has a different id, you can use a special SERVICEID:METHOD syntax:

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// src/AppBundle/Controller/HelloController.php

// You need to use Sensio's annotation to specify a service id
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;

/**
 * @Route(service="app.hello_controller")
 */
class HelloController
{
    // ...
}

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# app/config/routing.yml
hello:
    path:     /hello
    defaults: { _controller: app.hello_controller:indexAction }

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<!-- app/config/routing.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">
        <default key="_controller">app.hello_controller:indexAction</default>
    </route>

</routes>

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

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/AppBundle/Controller/Hello.php
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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# app/config/routing.yml
hello:
    path:     /hello/{name}
    defaults: { _controller: app.hello_controller }

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<!-- app/config/routing.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.hello_controller</default>
    </route>

</routes>

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

Alternatives to base Controller Methods

When using a controller defined as a service, you can still extend any of the normal base controller classes and use their 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 templating service and use it directly:

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

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

class HelloController
{
    private $twig;

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

    public function indexAction($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.