Symfony 2.0 getting service inside entity

You don't. This is a very common question. Entities should only know about other entities and not about the entity manager or other high level services. It can be a bit of a challenge to make the transition to this way of developing but it's usually worth it.

What you want to do is to load the role when you load the user. Typically you will end up with a UserProvider which does this sort of thing. Have you read through the sections on security? That should be your starting point:

http://symfony.com/doc/current/book/security.html

The reason why it's so difficult to get services into entities in the first place is that Symfony was explicitly designed with the intent that services should never be used inside entities. Therefore, the best practice answer is to redesign your application to not need to use services in entities.

However, I have found there is a way to do it that does not involve messing with the global kernel.

Doctrine entities have lifeCycle events which you can hook an event listener to, see http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/events.html#lifecycle-events For the sake of the example, I'll use postLoad, which triggers soon after the Entity is created.

EventListeners can be made as services which you inject other services into.

Add to app/config/config.yml:

services:
     example.listener:
           class: Alef\UserBundle\EventListener\ExampleListener
     arguments:
           - '@alef.role_service'
     tags:
           - { name: doctrine.event_listener, event: postLoad }

Add to your Entity:

 use Alef\UserBundle\Service\RoleService;

 private $roleService;

 public function setRoleService(RoleService $roleService) {
      $this->roleService = $roleService;
 }

And add the new EventListener:

namespace Alef\UserBundle\EventListener;

use Doctrine\ORM\Event\LifecycleEventArgs;
use Alef\UserBundle\Service\RoleService;

class ExampleListener
{
     private $roleService;

     public function __construct(RoleService $roleService) {
         $this->roleService = $roleService;
     }

     public function postLoad(LifecycleEventArgs $args)
     {
         $entity = $args->getEntity();
         if(method_exists($entity, 'setRoleService')) {
             $entity->setRoleService($this->roleService);
         }
     }
}

Just keep in mind this solution comes with the caveat that this is still the quick and dirty way, and really you should consider redesigning your application the proper way.

Thanks to Kai's answer above which answer to the question, but it's not compatible with symfony 5.x .

It's good to precise it's a bad practice, but required in some special case like legacy code or a bad DB design (as a temporary solution before schema migration)

As in my case, I use this code with a mailer and translator, which introduce an issue with the private property if Symfony >= 5.3 , so here the solution for recent version of symfony:

in config/services.yaml:

services:
    Alef\UserBundle\EventListener\ExampleListener:
        tags:
           - { name: doctrine.event_listener, event: postLoad }

ExampleListener:

namespace Alef\UserBundle\EventListener;

use Doctrine\ORM\Event\LifecycleEventArgs;
use Alef\UserBundle\Entity\Role;

class ExampleListener
{

    public function postLoad(LifecycleEventArgs $postLoad): void
    {
        $entity = $postLoad->getEntity();
        if ($entity instanceof User) {
            $repository = ;
            $entity->roleRepository(
                $postLoad->getEntityManager()->getRepository(Role::class)
            );
        }
    }
}

And in your Entity (or in a trait if you use it in more than one entity):

    use Alef\UserBundle\Service\RoleService;

    /** @internal bridge for legacy schema */
    public function roleRepository(?RoleRepository $repository = null) {
        static $roleRepository;
        if (null !== $repository) {
            $roleRepository = $repository;
        }
        return $roleRepository;
    }

    public function getRoleByName($name) {
        return $this->roleRepository()->findBy(array('name' => $name));
    }