public function childrensAction($id) {
        $em = $this->getDoctrine()->getManager();

        $parent = $em->getRepository('AmulenClassificationBundle:Category')->findOneBy(array("id" => $id));
        $childrens = $em->getRepository('AmulenClassificationBundle:Category')->getChildren($parent, true);

        return array(
            'entities' => $childrens,
            'parent' => $parent,
        );
    }