Symfony2 Doctrine2 postPersist on Associations

Question

Is there a way to get doctrine lifecycle events in symfony2 for an association field? http://docs.doctrine-project.org/projects/doctrine-orm/en/2.0.x/reference/events.html#lifecycle-events

eg:

Entity\User.php
..

 /**
 * @ORM\ManyToMany(targetEntity="Group", inversedBy="users", cascade={"persist"})
 * @ORM\JoinTable(name="users_groups",
 *      joinColumns={@ORM\JoinColumn(name="user_id", referencedColumnName="id", onDelete="CASCADE")},
 *      inverseJoinColumns={@ORM\JoinColumn(name="group_id", referencedColumnName="id", onDelete="CASCADE")}
 * )
 */
protected $groups;

So, when I create an event listener for the user http://symfony.com/doc/current/cookbook/doctrine/event_listeners_subscribers.html

Listener is called when Entity \ Group is added to Entity \ User.

NOTE. The only way to get this functionality is to create an Entity \ UserGroup and control this postpersist instead of PostPersist users.

Is this the only way to listen to entity associations?

! , getEntityChangeSet Event Args. getScheduledCollectionUpdates . :

EventListener\PostEventListener
..

public function postUpdate(LifecycleEventArgs $args)
{
  $this->handlePostEvents($args);
}


public function postPersist(LifecycleEventArgs $args)
{
  $this->handlePostEvents($args);
}

public function handlePostEvents(LifecycleEventArgs $args){
  $entity = $args->getEntity();
  $em = $args->getEntityManager();

  if ($entity instanceof User) {
    $uow = $em->getUnitOfWork();
    foreach ($uow->getScheduledCollectionUpdates() AS $col) {
      if ($col->first() instanceof Group) {
        // ADD CODE HERE
      }
    }
  }
}