Automapper 复杂映射从 List 到 Object

Question

I have object structure as below

public class Source
{
    public Connection Connection { get; set;}
}

public class Connection
{
    public string Id { get; set;
    public IEnumerable<Distributor> Distributors { get; set;
}

public class Distributor { get; set; }
{
    public DistributorType Type {get; set;}
    public  string X { get; set; }
    public string Y { get; set; }
}

public class Destination
{
     public Distribution Distribution { get; set;
}

public class Distribution
{
    public string Id { get; set;}
    public  string X { get; set; }
    public string Y { get; set; }
}

I would like to map the Source to Destination for the property Distribution. The mapping is as below

Source.Connection.Distributors.FirstOrDefault().X => Destination.Distribution.X
Source.Connection.Distributors.FirstOrDefault().Y => Destination.Distribution.Y
Source.Connection.Id => Destination.Distribution.Id 

I have tried using the Custom Resolver but no luck

public class CustomDistributorResolver : IValueResolver<Source, Destination, Distribution >
    {
        public Distribution  Resolve(Source source, Destination destination, Distribution destMember, ResolutionContext context)
        {
            var result = source.Connection.Distributors.FirstOrDefault(x => x.DistributorType =="ABC");
            if (result == null) return null;

            return new Distribution 
            {
                Id                      = source.Connection?.Id,
                X                       = result.X,
                Y                       = result.Y
            };
        }
    }

Mapping Pofile

CreateMap<Source, Destination>()
                .ForMember(d => d.Distribution, opt => opt.MapFrom( new CustomDistributorResolver()));

I always get Distribution value as NULL.

I am not sure what I am doing wrong here on mapping.

-Alan-

Answer 1

I am not very sure what you will deal with the IEnumerable. So I use linq to approach.

var id = Source.Connection.Id;
var distributions = Source.Connection.Distributors.Select(m=> new Distribution()
                    {
                            Id = id,
                            X = m.X,
                            Y = m.Y,
                    });

Automapper would like:

CreateMap<Source, Destination>()
    .ForMember(dest => dest.Distribution.Id ,opt => opt.MapFrom(src => src.Connection.Id))
    .ForMember(dest => dest.Distribution.X,  opt => opt.MapFrom(src => src.Connection.Distributors.FirstOrDefault().X))
    .ForMember(dest => dest.Distribution.Y,  opt => opt.MapFrom(src => src.Connection.Distributors.FirstOrDefault().Y));

Answer 2

You can use a type converter

private class DestinationConverter : ITypeConverter<Source, Destination>
{
    public Destination Convert(Source source,
    Destination destination,

    ResolutionContext context)
    {
        var result = source.Connection.Distributors.FirstOrDefault(x => x.Type == "ABC");

        if (result == null) return null;
        destination = new Destination();

        destination.Distribution = new Distribution
        {
            Id = source.Connection?.Id,
            X = result.X,
            Y = result.Y
        };

        return destination;
    }
}

and register the converter

CreateMap<Source, Destination>().ConvertUsing<DestinationConverter>();