手动配置对象映射，虽然麻烦但是具有可测试的有点。 One of the inspirations behind AutoMapper was to eliminate not just the custom mapping code, but eliminate the need for manual testing（AutoMapper虽然淘汰了手动配置映射，但是仍然保留了必须的可测试性）。因为映射是基于约定的，你仍需要测试你的配置。

AutoMapper 以 AssertConfigurationIsValid 方法的形式，提供配置测试。例如：

  1. public class Source
  2. {
  3.     public int SomeValue { get; set; }
  4. }
  6. public class Destination
  7. {
  8.     public int SomeValuefff { get; set; }
  9. }
  11. // 测试
  12. var configuration = new MapperConfiguration(cfg =>
  13.   cfg.CreateMap<Source, Destination>());
  15. configuration.AssertConfigurationIsValid();

执行测试代码会产生 AutoMapperConfigurationException 错误。AutoMapper检查以确保每个目标类型成员在源类型上都有一个对应成员。

重写配置错误

三种方式来解决这个错误：

自定义解析器（不推荐）：

  1. public interface IValueResolver<in TSource, in TDestination, TDestMember>
  2. {
  3.     TDestMember Resolve(TSource source, TDestination destination, TDestMember destMember, ResolutionContext context);
  4. }
  6. public class CustomResolver : IValueResolver<Source, Destination, int>
  7. {
  8.     // 可能不太对
  9.     public int Resolve(Source source, Destination destination, int member, ResolutionContext context)
  10.     {
  11.         return source.SomeValue;
  12.     }
  13. var configuration = new MapperConfiguration(cfg =>
  14.    cfg.CreateMap<Source, Destination>()
  15.      .ForMember(dest => dest.Total, opt => opt.MapFrom<CustomResolver>()));
  17. configuration.AssertConfigurationIsValid();

投影：

  1. var configuration = new MapperConfiguration(cfg =>
  2.   cfg.CreateMap<Source, Destination>());
  3. .ForMember(dest => dest.SomeValuefff, opt => opt.MapFrom(src => src.SomeValue))

忽视：

  1. var configuration = new MapperConfiguration(cfg =>
  2.   cfg.CreateMap<Source, Destination>());
  3. .ForMember(dest => dest.SomeValuefff, opt => opt.Ignore())