FSharpOptionObjectMapper.cs

public class FSharpOptionObjectMapper : IObjectMapper
{
    public object Map(ResolutionContext context, IMappingEngineRunner mapper)
    {
        var sourceValue = ((dynamic) context.SourceValue);

        return (sourceValue == null || OptionModule.IsNone(sourceValue)) ? null : sourceValue.Value;
    }

    public bool IsMatch(ResolutionContext context)
    {
        var isMatch = context.SourceType.IsGenericType &&
                      context.SourceType.GetGenericTypeDefinition() == typeof (FSharpOption<>);

        if (context.DestinationType.IsGenericType)
        {
            isMatch &= context.DestinationType.GetGenericTypeDefinition() != typeof(FSharpOption<>);
        }

        return isMatch;
    }
}
    
  ///
  /// in your setup / configuration of AutoMapper
  ///
    
var allMappers = AutoMapper.Mappers.MapperRegistry.AllMappers;
AutoMapper.Mappers.MapperRegistry.AllMappers = () => allMappers().Concat(new List<IObjectMapper>
    {
        new FSharpOptionObjectMapper()
    });
    
  ///
  /// Testing this
  ///
  
  [Test]
  public void FSharpOptionObjectMapper()
  {
      Mapper.CreateMap<SourceWithOption, DestinationWithNoOption>();
      var allMappers = AutoMapper.Mappers.MapperRegistry.AllMappers;
      AutoMapper.Mappers.MapperRegistry.AllMappers = () => allMappers().Concat(new List<IObjectMapper>
          {
              new DustAutomapper.FSharpOptionObjectMapper()
          });

      var id = new StudioId();
      var source1 = new SourceWithOption
      {
          Standard = "test",
          PropertyUnderTest = new FSharpOption<StudioId>(id)
      };

      var source2 = new SourceWithOption
      {
          Standard = "test"
      };

      var result1 = Mapper.Map<SourceWithOption, DestinationWithNoOption>(source1);
      Assert.AreEqual("test", result1.Standard, "basic property failed to map");
      Assert.AreEqual(id, result1.PropertyUnderTest, "TypeTypeConverter on BaseIdentiy didn't work as expected");

      var result2 = Mapper.Map<SourceWithOption, DestinationWithNoOption>(source2);
      Assert.AreEqual("test", result1.Standard, "basic property failed to map");
      Assert.IsNull(result2.PropertyUnderTest, "TypeTypeConverter for null failed");
  }


public class SourceWithOption
{
    public string Standard { get; set; }
    public FSharpOption<StudioId> PropertyUnderTest { get; set; }
}

public class DestinationWithNoOption
{
    public string Standard { get; set; }
    public StudioId PropertyUnderTest { get; set; }
}