AutoMapper map derived type to base type

Question

I am having some issues with AutoMapper and my current implementation of ASP.NET Identity.

My EF code first model resides in its own assembly (compiled with .NET 4.0 because of backwards compatibility with other software).

To use ASP.NET Identity (which needs at least .NET 4.5) I created a separate class in my webapplication which inherits from the database model class and implements IUser<MyUser, int>.

//DB-Assembly: .NET 4.0 Code-First Model
public class ModelUser 
{
    //omitted for brevity
} 

//Webapplication: .NET 4.5 -> because I want to use ASP.NET Identity
public class MyUser : ModelUser, IUser<MyUser, int> {}

//ASP.NET Identity UserStore implementation
public class UserStore : IUserStore<MyUser, int>
{
    //Works like a charm
    public Task UpdateAsync(MyUser user)
    {
        MyUser dbUser = _ctx.Users.Find(user.Id);
        ModelUser mappedUser = Mapper.Map(user, dbUser);
        _ctx.Users.AddOrUpdate(u => u.Id, mappedUser);
        return Task.FromResult(_ctx.SaveChanges());
    }

    //Throws "Mapping and metadata information could not be found for EntityType"
    public Task CreateAsync(MyUser user)
    {
        ModelUser dbUser = new ModelUser();
        ModelUser mappedUser = Mapper.Map(user, dbUser); //returns MyUser instead of ModelUser at runtime
        _ctx.Users.Add(mappedUser);
        return Task.FromResult(_ctx.SaveChanges());
    }
}

AutoMapper configuration in StartUp.cs:

Mapper.Initialize(cfg => cfg.CreateMap<ModelUser, MyUser>());

The default behavior from AutoMapper is to map to the most specific class. I want the opposite.

Does anyone know how to tell AutoMapper to map to a specific class or has any other suggestions how I can solve my problem?

Answer 1

AutoMapper.Mapper.CreateMap<ModelUser, MyUser>().ReverseMap(); 

We need to do reversemap to get ModelUser .