Symfony 2:如何处理表单中的嵌套集合

我正在尝试创建一个包含嵌套集合的表单。我不知道如何处理JS部分以显示子集合。有人知道我该怎么做吗？

这是我的表单代码：

class ParentFormType extends AbstractType 
{
    public function buildForm(FormBuilderInterface $builder, array $options) 
    {   
        $builder
              ->add('case', 'choice', array(
                        'choices'   => array(
                            'case1'   =>  'case1',
                            'case2'   =>  'case2',
                            'case3'   =>  'case3',
                )))
            ->add ('subForm1', 'collection', array (
             'type' => new Sub1FormType(),
             'allow_add' => true,
             'allow_delete' => true,
             'by_reference' => false,
             'prototype' => true,
            ))
    ;
        $builder->add('save',"submit") ;
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver) {
    }
    public function getName() {
        return 'formtestparenttype';
    }
}
class Sub1FormType extends AbstractType 
{
    public function buildForm(FormBuilderInterface $builder, array $options) 
    {   
        $builder
          ->add('fieldSub1',"text" )
          ->add ('childForm1', 'collection', array (
              'type' => new Sub2FormType,
              'allow_add' => true,
              'allow_delete' => true,
              'by_reference' => false,
              'prototype' => true,
          ))
          ;
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver) {
    }
    public function getName() {
        return 'formtestsub1type';
    }
}
class Sub2FormType extends AbstractType 
{
    public function buildForm(FormBuilderInterface $builder, array $options) 
    {   
        $builder
               ->add('fieldSub2',"text" )
          ;
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver) {
    }
    public function getName() {
        return 'formtesttype';
    }
}

控制器 ：

$form = $this->createForm(new ParentFormType() ) ;
return $this->render('MyBundle:Test:test.html.twig', array(
    'form' => $form->createView()
  ));

在这里; 树枝 + js 部分：

{% extends '::base.html.twig' %}
{% block content %}
{{ form_start(form) }} 
    <h3>Tags</h3>
    <ul class="collectionHolder" data-prototype="{{ form_widget(form.subForm1.vars.prototype)|e }}">
        {# iterate over each existing tag and render its only field: name #}
        {% for subForm1 in form.subForm1 %}
            <li>{{ form_row(subForm1) }} </li>
             <ul class="collectionHolder" data-prototype="{{ form_widget(subForm2.vars.prototype)|e }}">
            {%for subForm2 in subForm1.subForm2 %}
                <li>{{ form_row(subForm2) }}</li>
            {% endfor %}
        {% endfor %}
    </ul>
{{ form_end(form) }}

<script>
var $collectionHolder;
// setup an "add a tag" linkd
var $addTagLink = $('<a href="#" class="add_tag_link">Add</a>');
var $newLinkLi = $('<li></li>').append($addTagLink);
jQuery(document).ready(function() {
    function addTagForm($collectionHolder, $newLinkLi) 
    { 
        // Get the data-prototype explained earlier
        var prototype = $collectionHolder.data('prototype');
        // get the new index
        var index = $collectionHolder.data('index');
        // Replace '__name__' in the prototype's HTML to
        // instead be a number based on how many items we have
        var newForm = prototype.replace(/__name__/g, index);
        // increase the index with one for the next item
        $collectionHolder.data('index', index + 1);
        // Display the form in the page in an li, before the "Add a tag" link li
        var $newFormLi = $('<li></li>').append(newForm);
        $newLinkLi.before($newFormLi);
     }

    $collectionHolder = $('.collectionHolder');
    $collectionHolder.append($newLinkLi);
    // count the current form inputs we have (e.g. 2), use that as the new
    // index when inserting a new item (e.g. 2)
    $collectionHolder.data('index', $collectionHolder.find(':input').length);
    $addTagLink.on('click', function(e) {
        e.preventDefault();
        addTagForm($collectionHolder, $newLinkLi);
    });
});
</script>
{% endblock content %}