using System;

using AutoMapper;

public class Program

{

    public static void Main()

    {

        var a = new A() { Index = 1, Text = "Source", Ignored ="SourceIgnored", item= new Item() };

        var b = new B() { Index = 2, Text = "Destination", Ignored = "DestIgnored" };

        var config = new MapperConfiguration(cfg =>

        {

            var map = cfg.CreateMap<A, B>(MemberList.Source);

            map.ForMember(dest => dest.Text, opt => opt.UseDestinationValue());

            map.ForMember(dest => dest.Ignored, opt => opt.Ignore());

        });

​

        var mapper = config.CreateMapper();

        a = mapper.Map<A>(b);

        a.Dump();

    }

    public class A

    {

        public int Index { get; set; }

        public string Text { get; set; }

        public string Ignored { get; set; }

        public Item item {get; set;}

    }

​

    public class B

    {

        public int Index { get; set; }

        public string Text { get; set; }

        public string Ignored { get; set; }

    }

    public class Item

    {

        public string ItemString {get; set;}

    }

}