code: 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, selff 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)
docs: 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