Symfony2: Sonata Admin: Chained selectors, sonata_type_model_reference

Before today, I used custom AJAX to achieve this.

Client :

// Override of admin-bundle/Resources/Views/CRUD/base_edit.html.twig{% block javascripts %}  {{ parent() }}  <script type="text/javascript">    $(document).ready(function() {      $('#{{ admin.uniqId }}_parent').change(function() {        var parent = $(this);        var child = $('#{{ admin.uniqId }}_child');        $.get('/admin/child/get_choices/' + parent.val(), function(data) {          child.empty().append(data);        }, 'text')        .then(function() {          var childFirstOption = child.find('option:first');          var childDisplayText = $("#field_widget_{{ admin.uniqId }}_child .select2-chosen");          childFirstOption.attr("selected", true);          childDisplayText.text(childFirstOption.text());        });      });    });  </script>{% endblock %}

Server:

// src/App/AdminBundle/Controller/ChildAdminController.phpclass ChildAdminController extends Controller{    //...    public function getChoicesAction($parent)    {        $html = "";        $parent = $this->getDoctrine()            ->getRepository('AppAdminBundle:Parent')            ->find($parent)        ;        $choices = $parent->getChilds();        foreach($choices as $choice) {            $html .= '<option value="' . $choice->getId() . '" >' . $choice->getLabel() . '</option>';        }        return new Response($html);    }    //...}

And

// src/App/AdminBundle/Admin/ChildAdmin.php//...use Sonata\AdminBundle\Route\RouteCollection;class ChildAdmin extends Admin{    //...    protected function configureRoutes(RouteCollection $collection)    {        $collection->add('get_choices', 'get_choices/{parent}', array(), array(), array('expose' => true));    }    // ...}

I will try to implement sonata_type_model_reference soon and come back here for edits.