/**
  * @role update
  */
 public function sort()
 {
     foreach ($this->request->get($this->request->get('target'), array()) as $position => $key) {
         $class = ShippingClass::getInstanceByID((int) $key);
         $class->position->set((int) $position);
         $class->save();
     }
     return new JSONResponse(false, 'success');
 }