Automapper expression must resolve to top-level member - automapper

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. Parameter name: lambdaExpression
I am not able resolve the issue.
My source and destination objects are:
public partial class Source
{
private Car[] cars;
public Car[] Cars
{
get { return this.cars; }
set { this.cars = value; }
}
}
public partial class Destination
{
private OutputData output;
public OutputData Output
{
get { return this.output; }
set { this.output= value; }
}
}
public class OutputData
{
private List<Cars> cars;
public Car[] Cars
{
get { return this.cars; }
set { this.cars = value; }
}
}
I have to map Source.Cars with Destination.OutputData.Cars object. Could you please help me in this?

Answer 1

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 2

Define mapping between Source and OutputData.
Mapper.CreateMap<Source, OutputData>();
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)));

Answer 3

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 4

ForPath works for this exact scenario.
Mapper.CreateMap<Destination, Source>().ForPath(dst => dst.OutputData.Cars, e => e.MapFrom(src => src.Cars));

Answer 5

This worked for me:
Mapper.CreateMap<Destination, Source>()
.ForMember(x => x.Cars, x => x.MapFrom(y => y.OutputData.Cars))
.ReverseMap();

Answer 6

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.