public function execute()
 {
     $product_id = $this->get('product_id', true);
     $product_model = new shopProductModel();
     $product = $product_model->getById($product_id);
     if (!$product) {
         throw new waAPIException('invalid_param', 'Product not found', 404);
     }
     $product_pages_model = new shopProductPagesModel();
     $this->response = $product_pages_model->getByProductId($product_id);
     $this->response['_element'] = 'page';
 }