AutoMapper and inheritance – How to Map?

You will need to create DTO classes that match your domain classes like this:

public class DTO
{
    public string Name;
}

public class DTO_A : DTO
{
    public int Number { get; set; }
}

public class DTO_B : DTO
{
    public string Description { get; set; }
}

You then need to change your mappings to this:

        Mapper.CreateMap<Base, DTO>()
            .Include<ClassA, DTO_A>()
            .Include<ClassB, DTO_B>();

        Mapper.CreateMap<ClassA, DTO_A>();

        Mapper.CreateMap<ClassB, DTO_B>();

        Mapper.AssertConfigurationIsValid();

Once this is done, then the following will work:

        var baseList = new List<Base>
        {
            new Base {Name = "Base"},
            new ClassA {Name = "ClassA", Number = 1},
            new ClassB {Name = "ClassB", Description = "Desc"},
        };

        var test = Mapper.Map<IList<Base>,IList<DTO>>(baseList);
        Console.WriteLine(test[0].Name);
        Console.WriteLine(test[1].Name);
        Console.WriteLine(((DTO_A)test[1]).Number);
        Console.WriteLine(test[2].Name);
        Console.WriteLine(((DTO_B)test[2]).Description);
        Console.ReadLine();

Unfortunately this does mean that you have an unwanted cast, but I don’t think there’s much that you can do about that.