title: Symfony Form CollectionType, get the value of the active entry in entry_options
body: <p>In Symfony, I have a function <code>buildForm()</code> in an <code>AbstractType</code> extended Class, I use a <code>CollectionType</code>, and I want, to get the value of the active entry inside the <code>entry_options</code> array:</p>
  
  <p>Here's my code:</p>
  
  <pre><code>  if($options['data']-&gt;getDescription()-&gt;isEmpty()){
        $options['data']-&gt;getDescription()-&gt;set('fr',null);
        $options['data']-&gt;getDescription()-&gt;set('en',null);
     }
  
     $builder-&gt;add('description',CollectionType::class,array(
       'label'=&gt;'MyBundle.messages.description',
        'entry_type'=&gt;TextType::class,
        'entry_options'=&gt;array(
            'label'=&gt;'JCABundle.messages.language_name.'.[active entry value]
        )
     ));
  </code></pre>
  
  <p>My wish is to get [active entry value] substituted by 'fr' or 'en', knowing that 'description' (The attribute of the entity I use with my form) is an ArrayCollection that contains 'fr and 'en'.</p>
  
  <p>So it could display correctly: 'Français', 'Anglais' or 'French', 'English' instead of 'fr', 'en' as a label.</p>
  
  <p>Any idea?</p>