Form widget not bound to a Doctrine2 association? - symfony

Question

I have a form for creating a new BroadcastMessage entity and i need to display a widget of type <select multiple="multiple"> bound to excludedUsers property, not directly related to a Doctrine2 an association.
Inside my BroadcastMessageType class (inherits from AbstractType):
$builder->add('excludedUsers, 'entity', array(
'class' => 'Acme\MyBundle\Enrity\User',
'property' => 'username',
'multiple' => true
));
This of course works for creating a new BroadcastMessage; but on editAction i need a complex query to get excluded users. I need to compute excluded users looking for a record in a cross-reference table named broadcast_message_reference.
My question is fairly simple: where to add this "complex query" in order to get excludedUsers property correctly bound to the <select multiple="multiple"> widget? Inside my getExludedUsers method? If yes, how i'm supposed to access the entity repository for that query?
class BroadcastMessage
{
/**
* #ORM\Id
* #ORM\Column(type="integer")
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
private excludedUsers;
public function __costrunct()
{
$this->excludedUsers = new ArrayCollection();
}
public function addExcludedUser(Acme\MyBundle\Enrity\User $user)
{
$this->excludedUsers[] = $user;
return $this;
}
public function getExcludedUsers() { return $this->excludedUsers; }
}

Answer 1

Actually, I think, you need query_builder option within your form item definition:
$builder->add('excludedUsers', 'entity', array(
'class' => 'Acme\MyBundle\Enrity\User',
'property' => 'username',
'multiple' => true,
'query_builder' => function(EntityManager $em){
// you have an instance of EntityManager so you may build
// arbitrary QueryBuilder. Just remember to return it
// for example:
$qb = $em->createQueryBuilder()
->from('Acme\MyBundle\Enrity\User u')
->where('u.excluded = true');
return $qb;
},
'property' => 'username'
));
This is just rough example, but you can find more about entity form type here.

Answer 2

I think your problem can be solved by Form events. Create a service for EventSubscriber class, inject EntityManager and then subscribe for FormEvents::SET_DATA event.