public function actionCreateRoot()
 {
     if (isset($_POST['Classroom'])) {
         $new_root = new Classroom();
         $new_root->setAttributes($_POST['Classroom']);
         $relatedData = array('students' => $_POST['Classroom']['students'] === '' ? null : $_POST['Classroom']['students']);
         if ($new_root->saveNodeWithRelated($relatedData)) {
             echo json_encode(array('success' => true, 'id' => $new_root->primaryKey));
             exit;
         } else {
             echo json_encode(array('success' => false));
             exit;
         }
     }
 }