AutoMapper failing on on double

Question

I have the following classes

public class EstimationDTO
{
    public EstimationDTO() { }
    public EstimationDTO(double best, double mostLikely, double worst)
    {
        this.BestEffort = best;
        this.MostLikelyEffort = mostLikely;
        this.WorstEffort = worst;
    }
    public double BestEffort { get; set; }
    public double MostLikelyEffort { get; set; }
    public double WorstEffort { get; set; }
}
public class Estimation
{
    public Estimation() { }
    public Estimation(double best, double mostLikely, double worst)
    {
        this.BestEffort = best;
        this.MostLikelyEffort = mostLikely;
        this.WorstEffort = worst;
    }
    public double BestEffort { get; set; }
    public double MostLikelyEffort { get; set; }
    public double WorstEffort { get; set; }
}

And I have the following AutoMapper config

Mapper.CreateMap<EstimationDTO, Estimation>();
Mapper.CreateMap<Estimation, EstimationDTO>();

When I try to convert between the two ie

var x = Mapper.Map<EstimationDTO>(new Estimation{ BestEffort = 0.1, MostLikelyEffort = 0.2, WorstEffort = 0.3 });

automapper throws the following error:

AutoMapper.AutoMapperMappingException: Missing type map configuration or unsupported mapping.

Mapping types:
Estimation -> Double

(note that it throws the same error if I try the reverse conversion).
I tried doing explicit mapping for the properties, however this did not fix the issue.

If I specify the double conversion

Mapper.CreateMap<EstimationDTO, double>();
Mapper.CreateMap<Estimation, double>();

It works and properly converts between the two types.

How come I have to specify this specific conversion for the classes?

Answer 1

When using constructor arguments, you need to create explicit mappings that outline those constructor arguments with .ConstructUsing() (this example is in version 4.0.4).

void Main()
{
    Mapper.CreateMap<EstimationDTO, Estimation>()
        .ConstructUsing(
            (Func<EstimationDTO, Estimation>)(x => new Estimation(0.1, 0.2, 0.3)));

    Mapper.CreateMap<Estimation, EstimationDTO>()
        .ConstructUsing(
            (Func<Estimation, EstimationDTO>)(x => new EstimationDTO(0.1, 0.2, 0.3)));

    var mapped = Mapper.Map<EstimationDTO>(
        new Estimation{ BestEffort = 0.1, MostLikelyEffort = 0.2, WorstEffort = 0.3 });

    mapped.Dump();
}