PersistentCollection未初始化，但数据库中的数据使用Symfony和Doctrine

I have a problem with a PersistentCollection.

I have an Object User (herited of FOSUserbundle user class) who have an EmdebedDocument Seance. The Seance have an Array of Event. My Seance Class:

/**
* @MongoDB\EmbeddedDocument
*/
class Seance
{
/**
 * @MongoDB\Id
 */
protected $id;

/**
 * @MongoDB\EmbedMany(targetDocument="Event")
 */
protected $dispos ;

/**
 * @MongoDB\Field(type="string")
 */
protected $rayonDeplacement;

/**
 * @MongoDB\Field(type="string")
 */
protected $lieu;

/**
 * @MongoDB\Field(type="string")
 */
protected $prix;

/**
 * @MongoDB\Field(type="string")
 */
protected $nbPersonne;

And my class Event

/**
* @MongoDB\EmbeddedDocument
*/
class Event extends BaseEvent
{
/**
 * @var integer
 * @MongoDB\Id
 */
protected $id;

/**
 * @var \DateTime
 * @MongoDB\Field(type="date")
 * @Assert\NotNull()
 */
protected $startDate;
/**
 * @var \DateTime
 * @MongoDB\Field(type="date")
 * @Assert\NotNull()
 */
protected $endDate;

I give the event from user with:

$user->getSeance()->getDispos()

This function returns a empty PersistentCollection while they are events in database.

When dump the return of getDispos() method I have:

I dont't understant why I have mongoData field with my data but arrayCollection empty.

Thank you for yout help.

PersistentCollection is initialized lazily - for performance reasons, the data from database is held in mongoData. The collection is initialized during the first time you need some data from it (or try to modify it) - then the data held in mongoData is hydrated into your embedded documents and that is added to decorated coll. All this is happening transparently to you, just try using your collection instead of dumping it.