产品分类，只显示1层

app/Distributor/Controllers/DistProductCategoryController.php

@@ -77,7 +77,10 @@ class DistProductCategoryController extends AdminDistController
     {
         return Form::make(new DistProductCategory(), function (Form $form) {
             $form->select('parent_id', admin_trans_field('parent'))
-                ->options(DistProductCategory::selectOptionsShowTow())
+                ->options(DistProductCategory::selectMainOptions(function ($query) {
+                    // 在这里定义查询条件
+                    $query->where('parent_id', 0);
+                }))
                 ->saving(function ($v) {
                     return (int) $v;
                 });