php - Symfony 2.7 - Nested collections form types and choices -

i learning symfony 2 framework , struggling little bit on nested collections form types.

i trying build simple nested collections form entities modeled following:

mysurvey has many myquestions myquestions has many myanswer each myanswer holds possible value linked myquestion 

my objective have form displays questions survey , each question display available answer radio buttons (choices). able display answers text fields not choices...

here code:

here entities:

class mysurvey {     ....      /**      * @orm\manytomany(targetentity="myquestion")      * @orm\jointable(name="my_survey_questions",      *      joincolumns={@orm\joincolumn(name="survey_id", referencedcolumnname="id")},      *      inversejoincolumns={@orm\joincolumn(name="question_id", referencedcolumnname="id")}      *      )      */      protected $questions;  ... }  class myquestion {     ...      /**      * @orm\column(type="string", length=255)      */     protected $title;      /**      * @orm\manytomany(targetentity="myanswer")      * @orm\jointable(name="question_answers",      *      joincolumns={@orm\joincolumn(name="question_id", referencedcolumnname="id")},      *      inversejoincolumns={@orm\joincolumn(name="answer_id", referencedcolumnname="id")}      *      )      */      protected $answers;  ... }  class myanswer {     ....      /**      * @orm\column(type="string", length=255)      */     protected $value;  ... } 

here form types:

class mysurveyformtype extends abstracttype {     public function buildform(formbuilderinterface $builder, array $options)     {         $builder->add('questions', 'collection', array('type' => new myquestionformtype()));     }      ... }   class myquestionformtype extends abstracttype {     public function buildform(formbuilderinterface $builder, array $options)     {         $builder->add('answers', 'collection', array('type' => new myanswerformtype()));     }      ... }  class myanswerformtype extends abstracttype {     public function buildform(formbuilderinterface $builder, array $options)     {         $builder->add('value');     }      ... } 

and here template:

{% extends 'base.html.twig' %} {% block body %} <form  method="post" {{ form_enctype(form) }}>     {{ form_errors(form) }}     {% set = 0 %}     <ol>         {% question in form.questions %}             <br />             <li>                 {{ questions[i].title }}<br /><br />                 {% set j = 0 %}                 {% answer in question.answers %}                     {{ form_widget(question.answers[j]) }}                     {% set j = j + 1 %}                 {% endfor %}             {% set = + 1 %}             </li>        {% endfor %}     </ol>     <input type="submit" class="btn btn-primary" /> </form> {% endblock %} 

i tried change buildform function in myquestionformtype in order select proper answers question. in order solution working need have access answers of each questions, , don't know how done.

public function buildform(formbuilderinterface $builder, array $options) {      $builder->add('answers', 'entity', array(         'class' => 'appbundle:myanswer',         'choices' => ???      )); } 

if pass survey parameter in controller, there way "the current question" value in myquestionformtype can retrieve answers ?

$form = $this->createform(new mysurveyformtype($survey->getquestions()), $survey); 

any appreciated !

thanks lot