using AutoMapper;

using Newtonsoft.Json;

using System;

public class Program

{

    public static void Main()

    {

        var config = new MapperConfiguration(

            cfg =>

            cfg.CreateMap<Input, Output>()

                .ForMember("A", c => c.MapFrom("B"))

        );

        var mapper = config.CreateMapper();

​

        var input = new Input

        {

            A = Guid.NewGuid().ToString(),

            B = DateTime.UtcNow.ToString(),

            C = true.ToString()

        };

​

        Console.WriteLine(JsonConvert.SerializeObject(input));

        Console.WriteLine(JsonConvert.SerializeObject(mapper.Map<Output>(input)));

    }

}

​

public class Input

{

    public string A { get; set; }

    public string B { get; set; }

    public string C { get; set; }

}

​

public class Output

{

    public string A { get; set; }

    public DateTime B { get; set; }

    public bool C { get; set; }

}

​