Automapper expression must resolve to top-level member

Question

I am using automapper to map source and destination objects. While I map them I get the below error.

Expression must resolve to top-level member. Par

Answer 1

This worked for me:

Mapper.CreateMap<Destination, Source>()
    .ForMember(x => x.Cars, x => x.MapFrom(y => y.OutputData.Cars))
    .ReverseMap();

Answer 2

The correct answer given by allrameest on this question should help: AutoMapper - Deep level mapping

This is what you need:

Mapper.CreateMap<Source, Destination>()
    .ForMember(dest => dest.OutputData, opt => opt.MapFrom(i => i));
Mapper.CreateMap<Source, OutputData>()
    .ForMember(dest => dest.Cars, opt => opt.MapFrom(i => i.Cars));

When using the mapper, use:

var destinationObj = Mapper.Map<Source, Destination>(sourceObj)

where destinationObj is an instance of Destination and sourceObj is an instance of Source.

NOTE: You should try to move away from using Mapper.CreateMap at this point, it is obsolete and will be unsupported soon.

Answer 3

You are using :

 Mapper.CreateMap<Source, Destination>()
 .ForMember( dest => dest.OutputData.Cars, 
             input => input.MapFrom(i => i.Cars)); 

This won't work because you are using 2 level in the dest lambda.

With Automapper, you can only map to 1 level. To fix the problem you need to use a single level :

 Mapper.CreateMap<Source, Destination>()
 .ForMember( dest => dest.OutputData, 
             input => input.MapFrom(i => new OutputData{Cars=i.Cars})); 

This way, you can set your cars to the destination.

Answer 4

You can do it that way:

// First: create mapping for the subtypes
Mapper.CreateMap<Source, OutputData>();

// Then: create the main mapping
Mapper.CreateMap<Source, Destination>().
    // chose the destination-property and map the source itself
    ForMember(dest => dest.Output, x => x.MapFrom(src => src)); 

That's my way to do that ;-)

Answer 5

1. Define mapping between Source and OutputData.

   Mapper.CreateMap<Source, OutputData>();
   

2. Update your configuration to map Destination.Output with OutputData.

   Mapper.CreateMap<Source, Destination>().ForMember( dest => dest.Output, input => 
       input.MapFrom(s=>Mapper.Map<Source, OutputData>(s)));