/**
* Finds the Category model based on its primary key value.
* If the model is not found, a 404 HTTP exception will be thrown.
* @param integer $id
* @return Category the loaded model
* @throws NotFoundHttpException if the model cannot be found
*/
protected function findModel($id)
{
if ($id !== null && ($model = Category::findOne($id)) !== null) {
return $model;
} else {
throw new NotFoundHttpException('请求页面不存在');
}
}