Symfony 3: cannot access the container from inside a controller - php

Question

I'm migrating my app from Symfony 2.8 to Symfony 3.3.
From inside a controller of mine I have this:
public function indexAction()
{
$email = new Email();
$form = $this->createForm(GetStartedType::class, $email, [
'action' => $this->generateUrl('get_started_end'),
'method' => 'POST',
]);
return [
'form' => $form->createView(),
];
}
But I receive this exception:
Call to a member function get() on null
My controller extends Symfony\Bundle\FrameworkBundle\Controller\Controller:
/**
* {#inheritdoc}
*/
class DefaultController extends Controller
{
...
}
So I have access to the container.
Putting some dumps around in the Symfony's code, I see that the container is correctly set:
namespace Symfony\Component\DependencyInjection;
/**
* ContainerAware trait.
*
* #author Fabien Potencier <fabien#symfony.com>
*/
trait ContainerAwareTrait
{
/**
* #var ContainerInterface
*/
protected $container;
/**
* Sets the container.
*
* #param ContainerInterface|null $container A ContainerInterface instance or null
*/
public function setContainer(ContainerInterface $container = null)
{
dump('Here in the ContainerAwareTrait');
dump(null === $container);
$this->container = $container;
}
}
This dumps
Here in the ContainerAwareTrait
false
So the autowiring works well and sets the container.
But in the ControllerTrait I have this:
trait ControllerTrait
{
/**
* Generates a URL from the given parameters.
*
* #param string $route The name of the route
* #param mixed $parameters An array of parameters
* #param int $referenceType The type of reference (one of the constants in UrlGeneratorInterface)
*
* #return string The generated URL
*
* #see UrlGeneratorInterface
*/
protected function generateUrl($route, $parameters = array(), $referenceType = UrlGeneratorInterface::ABSOLUTE_PATH)
{
dump('Here in the ControllerTrait');
die(dump(null === $this->container));
return $this->container->get('router')->generate($route, $parameters, $referenceType);
}
...
this is the dump:
Here in the ControllerTrait
true
So here the container is null and this causes the error.
Anyone can help me solve this issue?
Why is the container null?
If may help, this is the services.yml configuration (the default that cames with Symfony):
# controllers are imported separately to make sure they're public
# and have a tag that allows actions to type-hint services
AppBundle\Controller\:
resource: '../../src/AppBundle/Controller'
public: true
tags: ['controller.service_arguments']
This question is posted as issue on the Symfony's issue tracker.

Answer 1

The S3.3 autowire capability makes it a bit easier to define controllers as services.
The usual motivation behind defining controllers as services is to avoid injecting the container. In other words you should be explicitly injecting each service a controller uses. The autowire capability allows you to use action method injection so you don't have to inject a bunch of stuff in the constructor.
However, the base Symfony controller class provides a number of helper function which use about 12 different services. It would be painful indeed to inject these one at a time. I had sort of thought that the autowire capability might take care of this for you but I guess not.
So you basically need to add a call to setContainer in your service definition. Something like:
AppBundle\Controller\:
resource: '../../src/AppBundle/Controller'
public: true
[[setContainer, ['#service_container']]]
tags: ['controller.service_arguments']
The autowire capability is very much a work in progress so I would not be surprised if this changes for 3.4/4.0.

Answer 2

This problem is fixed by PR #23239 and is relased in Symfony 3.3.3.