Symfony2 : Binding an expanded multiple choice form

Question

I set up a form which includes a multiple expanded form

$builder->add('rooms', 'entity', array(
        'class' => 'MyBundle:House',
        'multiple' => true,
        'expanded' => true,
        'required' => false
));

The underlying class House has a rooms attribute defined as a many-to-many relation

/**
 * @ORM\ManyToMany(targetEntity="RoomsType", cascade={"all"}) 
 */
private $rooms;

public function __construct()
{
    $this->rooms = new \Doctrine\Common\Collections\ArrayCollection();
}

public function addRooms($room)
{
    $this->rooms[] = $room;
}

public function getRooms()
{
    return $this->rooms;
}

When I render the form

{{ form_row(form.rooms }}

and then submit the form, I meet the following exception: Expected argument of type 'array' 'string' given (500 Internal Server Error)

If the form is not configured as a expanded, no exception is raised and the binding between the form and the underlying object works fine.

Any idea ?

Answer 1

Your targetEntity for your relationship has an odd name of RoomsType. Are you certain your Entity is RoomsType and not just Rooms? I would expect your RoomsType to define the form for your Rooms entity