if( $role_ids ){
                      
                     $model_user_role_arr = [];//初始化数组
                     foreach( $role_ids as $key=>$_role_id ){//将需要插入的数据放入数组
                         
                         $model_user_role_arr[$key]['uid'] = $model_user->id;
                         $model_user_role_arr[$key]['role_id'] =  $_role_id;
                         $model_user_role_arr[$key]['created_time'] =  $date_now;
                     }
                     //在将数组写入数据库
                     $UserRole = new UserRole();
                     \Yii::$app->db->createCommand()->batchInsert(
                         UserRole::tableName(),
                         ['uid','role_id','created_time'], 
                         $model_user_role_arr
                     )->execute(); 
                }

视频中的 循环写入数据库，替换成上面的方式也行。