def ajax_subcat_arr(self, pid):
        '''
        Get the sub category.
        ToDo: The menu should display by order. Error fond in DRR.

        根据父类ID（pid）获取子类，返回Json格式
        '''
        out_arr = {}
        for catinfo in MCategory.query_sub_cat(pid):
            out_arr[catinfo.uid] = catinfo.name
        json.dump(out_arr, self)
Get the sub category.
        ToDo: The menu should display by order. Error fond in DRR.

        根据父类ID（pid）获取子类，返回Json格式