AutoMapAlternative.cs

using System;
using System.Collections.Generic;

namespace Next.Whs.DDespatch.Framework.Models.Mapping.Custom
{
    public class ExampleImplementationClass
    {
        public ExampleImplementationClass()
        {
            MapperBase<Entity, DTO> userMapper = new UserMapper();
            var users = new List<Entity>();
            List<DTO> userDtos = userMapper.Map(users, delegate (DTO u)
            {
                //Update UserDto object here
                u.UserAddress = "";
            });
        }
    }

    public class Entity
    {
        public string Name { get; set; }
        public string Address { get; set; }
    }

    public class DTO
    {
        public string UserName { get; set; }
        public string UserAddress { get; set; }
    }

    public abstract class MapperBase<TFirst, TSecond>
    {
        public abstract TFirst Map(TSecond element);
        public abstract TSecond Map(TFirst element);

        public List<TFirst> Map(List<TSecond> elements, Action<TFirst> callback = null)
        {
            var objectCollection = new List<TFirst>();
            if (elements != null)
            {
                foreach (TSecond element in elements)
                {
                    TFirst newObject = Map(element);
                    if (newObject != null)
                    {
                        callback?.Invoke(newObject);

                        objectCollection.Add(newObject);
                    }
                }
            }
            return objectCollection;
        }

        public List<TSecond> Map(List<TFirst> elements, Action<TSecond> callback = null)
        {
            var objectCollection = new List<TSecond>();

            if (elements != null)
            {
                foreach (TFirst element in elements)
                {
                    TSecond newObject = Map(element);
                    if (newObject != null)
                    {
                        callback?.Invoke(newObject);
                        objectCollection.Add(newObject);
                    }
                }
            }
            return objectCollection;
        }
    }

    public sealed class UserMapper : MapperBase<Entity, DTO>
    {
        public override Entity Map(DTO element)
        {
            return new Entity
            {
                Name = element.UserName,
                Address = element.UserAddress
            };
        }

        public override DTO Map(Entity element)
        {
            return new DTO
            {
                UserName = element.Name,
                UserAddress = element.Address
            };
        }
    }
}