php - set multiple='false' in a form in a many to many relation symfony2 -

i have many-to-many relationship between 2 entities , b.

so when adding form, in order add entitya entityb, doing following:

$builder               ->add('entityas', 'entity', array(       'class'    => 'xxxbundle:entitya',       'property' => 'name',       'multiple' => true,     ));} 

and alright.

but depending on field type of entitya, want set 'multiple' false, i'm doing following :

if($type=='a'){     $builder                   ->add('entityas', 'entity', array(           'class'    => 'xxxbundle:entitya',           'property' => 'name',           'multiple' => true,         ));}  else {     $builder                   ->add('entityas', 'entity', array(           'class'    => 'xxxbundle:entitya',           'property' => 'name',           'multiple' => false,          )); } 

this gives me following error:

catchable fatal error: argument 1 passed doctrine\common\collections\arraycollection::__construct() must array, object given, called in c:\wamp\www\symfony\vendor\doctrine\orm\lib\doctrine\orm\unitofwork.php on line 519 , defined in c:\wamp\www\symfony\vendor\doctrine\common\lib\doctrine\common\collections\arraycollection.php line 48  

can me?

in entitya, have this, right?

public function setentitiesb($data) {     $this->entitiesb = $data ; } 

now because can receive single value instead of array of values, need this:

public function setentitiesb($data) {     if ( is_array($data) ) {         $this->entitiesb = $data ;     } else {         $this->entitiesb->clear() ;         $this->entitiesb->add($data) ;     } }