symfony - Extending EntityType to allow extra choices set with AJAX calls -

i try create symfony custom type extending core "entity" type.

but want use select2 version 4.0.0 (ajax works "select" html element , not hidden "input" before).

• this type should create empty select instead of full list of entities extended "entity" type.

this works setting option (see configureoption):

'choices'=>array() 

• by editing object attached form should populate select current data of object. solved problem view following buildview method ...

select2 recognize content of html "select", , work ajax. when form posted back, symfony doesn't recognize selected choices, (because there not allowed ?)

symfony\component\form\exception\transformationfailedexception      unable reverse value property path "user": choice "28" not exist or not unique 

i tried several methods using eventlisteners or subscribers can't find working configuration.

with select2 3.5.* solved problem form events , overriding hidden formtype, here extending entitytype more difficult.

how can build type let manage reverse transformation of entites ?

custom type :

<?php namespace appbundle\form\type;  use symfony\component\form\abstracttype; use symfony\component\form\formbuilderinterface; use symfony\component\form\formview; use symfony\component\form\forminterface; use symfony\component\optionsresolver\optionsresolver;  use symfony\component\form\choicelist\view\choiceview;  class ajaxentitytype extends abstracttype {     protected $router;      public function __construct($router)     {         $this->router = $router;     }     /**     * {@inheritdoc}     */     public function buildform(formbuilderinterface $builder, array $options)     {            $builder->setattribute('attr',array_merge($options['attr'],array('class'=>'select2','data-ajax--url'=>$this->router->generate($options['route']))));     }      /**     * {@inheritdoc}     */     public function buildview(formview $view, forminterface $form, array $options)     {         $view->vars['attr'] = $form->getconfig()->getattribute('attr');         $choices = array();         $data=$form->getdata();         if($data instanceof \doctrine\orm\persistentcollection){$data = $data->toarray();}         $values='';         if($data != null){             if(is_array($data)){                 foreach($data $entity){                     $choices[] = new choiceview($entity->getajaxname(),$entity->getid(),$entity,array('selected'=>true));                 }             }             else{                 $choices[] = new choiceview($data->getajaxname(),$data->getid(),$data,array('selected'=>true));             }         }          $view->vars['choices']=$choices;     }     /**     * {@inheritdoc}     */     public function configureoptions(optionsresolver $resolver)     {         $resolver->setrequired(array('route'));         $resolver->setdefaults(array('choices'=>array(),'choices_as_value'=>true));     }      public function getparent() {         return 'entity';     }      public function getname() {         return 'ajax_entity';     } } 

parent form

<?php namespace appbundle\form;  use symfony\component\form\abstracttype; use symfony\component\form\formbuilderinterface; use symfony\component\optionsresolver\optionsresolver;  class alarmstype extends abstracttype {    /**      * @param formbuilderinterface $builder      * @param array $options      */     public function buildform(formbuilderinterface $builder, array $options)     {         $builder             ->add('name','text',array('required'=>false))             ->add('user','ajax_entity',array("class"=>"appbundle:users","route"=>"ajax_users"))             ->add('submit','submit');     }      /**      * @param optionsresolver $resolver      */     public function configureoptions(optionsresolver $resolver)     {         $resolver->setdefaults(array('data_class' => 'appbundle\entity\alarms','validation_groups'=>array('default','form_user')));     }      /**      * @return string      */     public function getname()     {         return 'alarms';     } } 

problem solved.

the solution recreate form field 'choices'=>$selectedchoices in both pre_set_data , pre_submit formevents.

selected choices can retrived event $event->getdata()

have on bundle created, implements method :

alsatian/formbundle - extensiblesubscriber