symfony2 form with a many to many entity - symfony

Question

I have this form with manyTomany relation working perfectly like this:
public function buildForm(FormBuilderInterface $builder, array $options) {
$builder
->add('manifestations', 'entity', array(
'class' => 'PrifProtocoleBundle:Manifestation',
'multiple' => true,
'expanded' => false,
'property' => 'libelle',
'empty_value' => 'Choississez',
'required' => false,));
}
but i want to set the'multiple' parameter to 'false', this way, i just have a select box with the option 'Choississez', so when i click on it, it displays all the other values. Unfortunately i get an error message: nor of the methods _set()" or "_call()" exist and have public access in class. i've been searching for some solutions on the web and tried this one:
public function buildForm(FormBuilderInterface $builder, array $options) {
$builder
->add('manifestations', 'collection', array(
'type' => 'entity',
'options' => array(
'class' => 'AcmeProtoBundle:Manifestation',
'multiple' => false,
'expanded' => false,
'property' => 'libelle',
'empty_value' => 'Choisissez',
'required' => false,)));
}
i have no error message! but the select form doesn't display even when i set the 'multiple' to 'true, i only have the submit button, when clicked shows me the results, so i think i miss something in the parameters to display the form!
can anyone help? Thanks
Manifestation.php
/**
* #ORM\Entity
* #ORM\Entity(repositoryClass="ManifestationRepository")
*/
class Manifestation {
public function __construct() {
$this->dateCreation = new \DateTime;
$this->dateModif = new \DateTime;
}
public function __toString() {
return $this->getLibelle();
}
/**
* #ORM\GeneratedValue(strategy="AUTO")
* #ORM\Id
* #ORM\Column(type="integer")
*/
private $id;
/**
* #ORM\Column(type="integer")
* #Assert\GreaterThan(
* value = 0,
* message = "La valeur doit être positive"
* )
*/
private $numOrdre;
/**
* #ORM\Column(type="string",length=50)
* #Assert\Length(
* min = "5",
* minMessage = "Le libellé doit faire au moins {{ limit }} caractères"
* )
*/
private $libelle;
/**
* #ORM\Column(type="datetime")
*/
private $dateCreation;
/**
* #ORM\Column(type="datetime")
*/
private $dateModif;
/**
* #ORM\Column(type="boolean")
* #Assert\NotBlank( message=" ")
*/
private $etat;
//getters and setters
invite.php
/**
* #ORM\Entity
* #ORM\Entity(repositoryClass="InviteRepository")
*
*/
class Invite {
/**
* #var boolean
*
* #ORM\ManyToMany(targetEntity="Acme\ProtoBundle\Entity\Manifestation", cascade={"persist"})
* #Assert\NotBlank(message=" ")
*/
private $manifestations;

Answer 1

Can you show your manifestation.php file (your entity)?
Multiple doesn't have the behaviour you are looking for : Multiple is used to allow a user to check multiple checkboxes (true) or only one (false) of a given form (symfony doc : multiple).
In your case a common solution is to use javascript on a parent field that would disable/enable the children fields. Make sure to add server-side validation on these fields if you go for this.

Answer 2

This is the solution working for me now with 'multiple' => false':
i've added this function in the other entity in relation with Manifestation, to consider manifestations as an array
public function setManifestations($manifestations){
if(!is_array($manifestations)){
$manifestations = array($manifestations);
}
$this->manifestations = $manifestations;
}