grid增加过滤条件

app/Admin/Controllers/CategoryController.php

@@ -41,8 +41,9 @@ class CategoryController extends AdminController
             $grid->column('sort');
 
             $grid->filter(function (Grid\Filter $filter) {
-                $filter->equal('id');
+				$filter->model()->where('agent_id', 0);
 
+                $filter->equal('id');
             });
         });
     }