#nullable enable

using System;

using AutoMapper;

​

#region Child

​

public class ChildSourceBase

{

}

​

public class ChildDestinationBase

{

    public ParentDestination Parent { get; set; } = null!;

}

​

​

public class ChildSourceMiddle : ChildSourceBase

{

}

​

public class ChildDestinationDerived : ChildDestinationBase

{

}

​

​

public class ChildSourceDerived : ChildSourceMiddle

{

}

​

#endregion

​

#region Parent

​

public class ParentSourceBase

{

}

​

public class ParentDestination

{

    public ChildDestinationBase Child { get; set; } = null!;

}

​

​

public class ParentSourceDerived : ParentSourceBase

{

    public ChildSourceDerived Child { get; set; } = null!;

}

​

#endregion

​

public class Program

{

    public static void Main()

    {

        var config = new MapperConfiguration(cfg => {

            #region Parent

            cfg.CreateMap<ParentSourceBase, ParentDestination>()

                .ForMember(dest => dest.Child, opt => opt.Ignore());

            cfg.CreateMap<ParentSourceDerived, ParentDestination>()

                .IncludeBase<ParentSourceBase, ParentDestination>()

                .ForMember(dest => dest.Child, opt => opt.MapFrom(src => src.Child))

                ;

            #endregion

            #region Child

            cfg.CreateMap<ChildSourceBase, ChildDestinationBase>()

                .ForMember(dest => dest.Parent, opt => opt.Ignore());

            cfg.CreateMap<ChildSourceMiddle, ChildDestinationDerived>()

                .IncludeBase<ChildSourceBase, ChildDestinationBase>();

            cfg.CreateMap<ChildSourceDerived, ChildDestinationDerived>()

                .IncludeBase<ChildSourceMiddle, ChildDestinationDerived>();

            #endregion

        });     

        config.AssertConfigurationIsValid();

    }

}