调整admin下的类库代码，将主要逻辑调整到extend下

extend/base/admin/model/MallGoodsClass.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace base\admin\model;
+
+use app\admin\model\MallTag;
+use app\common\model\TimeModel;
+
+class MallGoodsClass extends TimeModel
+{
+    protected $deleteTime = 'delete_time';
+
+    public function cate()
+    {
+        return $this->belongsTo('app\admin\model\MallCate', 'cate_id', 'id');
+    }
+
+    public function getTagListTitleAttr()
+    {
+        $tags = $this->getAttr('tag');
+
+        $list_tag = MallTag::whereIn('id', $tags)->column('title');
+
+        return $list_tag;
+    }
+}