anchor.diff:  
   %% 更新数据，返回ok | notfound
   update(Table, M) ->
  +    case ss_model:validate(M) of
  +        {ok, _} -> update2(Table, M);
  +        {error, M2} -> {error, M2}
  +    end.
  +update2(Table, M) ->
       Id = maps:get(value, proplists:get_value(<<"_key">>, M)),
       init(Table),
       OldData = from_model(get(Table, Id)),
  
positive.code:     Data1 = from_model(M),
      Data = maps:merge(OldData, Data1#{<<"_lastmodified_at">> => Time}),
      dets:insert(Table, {Id, Data}),
      close(Table).
  
  %% 部分更新
  patch(Table, M) ->
  
negative.code: %% Data应为maps类型
  %% 自动插入创建和最后修改时间时间戳, 使用ISO标准格式
  create(Table, M) ->
      case ss_model:validate(M) of
          {ok, _} -> create2(Table, M);
          {error, M2} -> {error, M2}
      end.
  create2(Table, M) ->
      Id1 = maps:get(value, proplists:get_value(<<"_key">>, M, #{}), undefined),
      if
          Id1 =:= undefined ->
  