update

@@ -24,6 +24,7 @@ class CategoryLogic extends  BaseLogic
     }
 
     public function save($param){
+        $param['pid'] = $param['pid'] ?? 0;
         if(!empty($param['pid'])){
             if(!empty($param['id']) && $param['pid'] == $param['id']){
                 $this->fail('上级分类不能是本分类');