Symfony2 , Container Service - symfony

Question

Hello i have an error on EventSubscriber for form in sonata admin
namespace OneA\AdvertBundle\Form\EventListener;
use Symfony\Component\Form\FormFactoryInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\DependencyInjection\ContainerAware;
class CategoryFieldsSubscriber extends ContainerAware implements EventSubscriberInterface
{
private $factory;
public function __construct(FormFactoryInterface $factory)
{
$this->factory = $factory;
}
public static function getSubscribedEvents()
{
return array(FormEvents::PRE_SET_DATA => 'preSetData');
}
public function preSetData(FormEvent $event)
{
$data = $event->getData();
$form = $event->getForm();
//$form->add('advert_fields', 'text');
$advert_type = $form->get('advert_type')->getData();
$this->getFields($form, $advert_type);
}
public function getFields($form, $advert_type)
{
$form->add('advert_fields', 'text', array(
'label' => 'dfjg',
));
$this->container->get('one_a_advert.admin_motors_field')->getFieldsForm($form);
}
}
When i call the container i have this error
FatalErrorException: Error: Call to a member function get() on a non-object in
To the container->get(

Answer 1

You need to send in your constructor required container like this:
services:
kernel.listener.your_listener:
class: OneA\AdvertBundle\Form\EventListener\CategoryFieldsSubscriber
arguments: [#factory, #service_container]
and use this like
private $container;
private $factory;
public function __construct(FormFactoryInterface $factory, $container)
{
$this->container = $container;
$this->factory = $factory;
}