title: Symfony2 - Entire child entity in form and Twig template
body: <p>In a Sonata admin form, I'd like to display all images related to the current object. Don't need to edit them.
  I managed to get this working with an entity field type and its property option to select the image URL as label so I can call all pictures in the template :</p>
  
  <pre><code>-&gt;add('image', 'entity', array(
      'class' =&gt; 'Hop\HopBundle\Entity\Image',
      'property' =&gt; 'image_url',
      'query_builder' =&gt; function($er) use ($object) {
          return $er-&gt;createQueryBuilder('i')
          -&gt;where('i.object = :object')
          -&gt;setParameter('object', $object)
          ;
      },
      'expanded' =&gt; true,
  ))
  </code></pre>
  
  <p>.</p>
  
  <pre><code>{% for child in form %}
      &lt;img src="{{ child.vars.label }}" alt="{{ child.vars.label }}" /&gt;
  {% endfor %}
  </code></pre>
  
  <p>It's because it seems that the entity type only give label and one value to the template.</p>
  
  <p>But I'd like to get also image width, descriptions, date, ... In other word : how can we get each entire related image object in the Twig template ?</p>
  
  <p>Thanks.</p>