Automapper项目使用 [英] Automapper Project using

问题描述

我当前在后端使用automapper来将对象映射到模型. 我最近决定使用以下代码来处理我所有的时区转换:

I am currently using automapper in my backend to map objects to models. I recently decided to use the following code to handle all my timezone conversions:

  cfg.CreateMap<DateTime?, DateTime?>()
  .ProjectUsing(i => DbFunctions.AddHours(i, offset.Hours));

  cfg.CreateMap<DateTime, DateTime>()
  .ProjectUsing(i => DbFunctions.AddHours(i, offset.Hours).Value);


  Object.ProjectTo<ObjectModel>().SingleOrDefault();

然后正常工作，并映射对象并转换时区

then it works fine and the object is mapped and timezone converted

但是，当我在业务层中使用以下代码进行单个对象映射时:

However when i am using the following code in my business layer to do a single object mapping:

Mapper.Map<Object, ObjectModel>(singleRecord); 

它给出一个错误: 此函数只能从LINQ到Entities调用.

It Gives an error : This function can only be invoked from LINQ to Entities.

堆栈跟踪:

at System.Data.Entity.DbFunctions.AddHours(Nullable`1 timeValue, Nullable`1 addValue)
   at lambda_method(Closure , DateTime , DateTime , ResolutionContext )
   at AutoMapper.ResolutionContext.Map[TSource,TDestination](TSource source, TDestination destination)
   at lambda_method(Closure , Inventory , InventoryModel , ResolutionContext )

Mapper.Map对于在特定情况下使用非常重要，我也不想投影单个记录.

Mapper.Map is important to use in specific scenarios and i also don't want to project single records.

有办法解决吗?

推荐答案

默认情况下，AutoMapper将通过编译传递给ProjectUsing并由ProjectTo，因为通常就足够了并且可以正常工作.但是没有EF规范功能.

By default AutoMapper will build a mapping Func<TSource, TDestination>> to be used by Map method by compiling the Expression<TFunc<TSource, TDestionation>> passed to ProjectUsing and used by ProjectTo, because usually it's enough and works. But not with EF canonical functions.

您可以通过显式提供ProjectUsing和ConvertUsing来指定与Map方法一起使用的另一种转换来覆盖该行为:

You could override that behavior by specifying a different conversion to be used with Map method by providing explicitly both ProjectUsing and ConvertUsing:

var map1 = cfg.CreateMap<DateTime?, DateTime?>();
map1.ProjectUsing(i => DbFunctions.AddHours(i, offset.Hours));
map1.ConvertUsing(i => i?.AddHours(offset.Hours));

var map2 = cfg.CreateMap<DateTime, DateTime>();
map2.ProjectUsing(i => DbFunctions.AddHours(i, offset.Hours).Value);
map2.ConvertUsing(i => i.AddHours(offset.Hours));

这篇关于Automapper项目使用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！