Automapper not mapping from a source containing a single nullable boolean field

Question

I'm seeing some very strange behaviour in Automapper when mapping from a object with a single Nullable<bool> property. I currently have it set up like this:

public class MyViewModel
{
    public bool? IsAThing { get; set; }
}

public class MyEntity
{
    public bool? IsAThing { get; set; }

    public bool? HasAnotherThing { get; set; }

    public string AnotherThing { get; set; }

    // Lots of other fields
}

with the following mapping profile (with a similar reverse mapping):

CreateMap<MyViewModel, MyEntity>()
    .ForMember(x => x.IsAThing, opt => opt.MapFrom(y => y.IsAThing))
    .ForAllOtherMembers(opt => opt.Ignore());

However if I try to do the following:

var config = new AutoMapperConfig().Configure();
var mapper = config.CreateMapper();

var source = new MyViewModel { IsAThing = true };
var dest = new MyEntity();

mapper.Map(source, dest);

dest.IsAThing is null. The mapping profile is the only place where MyViewModel is declared as a mapping source. Strangely, if I declare the class

public class AnotherThingViewModel
{
    public bool? HasAnotherThing { get; set; }
    public string AnotherThing { get; set; }
}

And do the following test:

var source = new AnotherThingViewModel { HasAnotherThing = true };
var dest = new MyEntity();
mapper.Map(source, dest);

dest.HasAnotherThing is true as expected!

Obviously I have no idea what's going on here so has anyone seen anything like this before, or knows of any bugs in Automapper that might cause this?

Can't reproduce this with provided code and last (6.1.1) version of automapper nuget package (that is - dest.IsAThing is true and not null). — Evk
Please edit your question to include a MCVE so we can see/test the source code you have. — Progman

Mourndark Mourndark · Accepted Answer · 2017-10-16T10:27:15

I figured it out, I had CreateMap<MyViewModel, MyEntity>().ForAllMembers(opt => opt.Ignore()) elsewhere in my mapping configuration!

Automapper not mapping from a source containing a single nullable boolean field

1 Answers