使用Automapper的BeforeMap方法，在映射前进行额外操作。

示例代码：

public class OuterSource { public int Id { get; set; } public InnerSource Inner { get; set; } }

public class InnerSource { public string Name { get; set; } }

public class OuterDest { public int Id { get; set; } public InnerDest Inner { get; set; } }

public class InnerDest { public string Name { get; set; } }

public class MappingProfile : Profile { public MappingProfile() { CreateMap().BeforeMap((src, dest) => { // Do something before mapping dest.Id = src.Id + 100; }) .ForMember(dest => dest.Inner, opt => opt.MapFrom(src => src.Inner));

    CreateMap();
}

}

// 使用示例 var source = new OuterSource { Id = 1, Inner = new InnerSource { Name = "inner" } }; var mapper = new MapperConfiguration(cfg => cfg.AddProfile()).CreateMapper(); var dest = mapper.Map(source);

Console.WriteLine(dest.Id); // 输出 101 Console.WriteLine(dest.Inner.Name); // 输出 inner