anchor.diff:  %% 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 ->
  
positive.code: 
  %% 更新数据，返回ok | notfound
  update(Table, M) ->
      Id = maps:get(value, proplists:get_value(<<"_key">>, M)),
      init(Table),
      OldData = from_model(get(Table, Id)),
  
negative.code:     Data1 = from_model(M),
      Data = maps:merge(OldData, Data1#{<<"_lastmodified_at">> => Time}),
      dets:insert(Table, {Id, Data}),
      close(Table),
      ok.
  
  %% 部分更新
  patch(Table, M) ->
  