问题:

I am trying to map objects with multi-level members: these are the classes:

 public class Father
    {
        public int Id { get; set; }
        public Son Son { get; set; }
    }

    public class FatherModel
    {
        public int Id { get; set; }
        public int SonId { get; set; }
    }

    public class Son
    {
        public  int Id { get; set; }
    }

This is how I try automap it:

 AutoMapper.Mapper.CreateMap<FatherModel , Father>()
                      .ForMember(dest => dest.Son.Id, opt => opt.MapFrom(src => src.SonId));

this is the exception that I get:

Expression 'dest => Convert(dest.Son.Id)' must resolve to top-level member and not any child object's properties. Use a custom resolver on the child type or the AfterMap option instead. Parameter name: lambdaExpression

Thanks

回答1:

This will work both for mapping to a new or to an existing object.

Mapper.CreateMap<FatherModel, Father>()
    .ForMember(x => x.Son, opt => opt.MapFrom(model => model));
Mapper.CreateMap<FatherModel, Son>()
    .ForMember(x => x.Id, opt => opt.MapFrom(model => model.SonId));

回答2:

    AutoMapper.Mapper.CreateMap<FatherModel, Father>()
                     .ForMember(x => x.Son, opt => opt.ResolveUsing(model => new Son() {Id = model.SonId}));

if it's getting more complex you can write a ValueResolver class, see example here- http://automapper.codeplex.com/wikipage?title=Custom%20Value%20Resolvers