using System;

using System.Text.Json;

using AutoMapper;

public class Program

{

    public static void Main()

    {

        MapperConfiguration config = new MapperConfiguration(cfg => 

                                                             {

                                                                cfg.AddProfile<MappingProfile>(); 

                                                             });

        IMapper mapper = config.CreateMapper();

        Note src = new Note

        {

            //Agent = "Agent",

            AssociatedFirm = "AssociatedFirm",

            //Review = "Review",

            Schedule = "Schedule",

            //Participant = "Participant",

        };

        NoteVM dest = mapper.Map<NoteVM>(src);

        Console.WriteLine(JsonSerializer.Serialize(dest, new JsonSerializerOptions { WriteIndented = true }));

    }

}

​

public class MappingProfile : Profile

{

    public MappingProfile()

    {

​

         CreateMap<Note, NoteVM>()

                  .ForMember(d => d.NoteParent, opt => opt.MapFrom((src, dest, destMember, ctx) => 

                      {

                            if (src.Agent != null)

                                return "Agent";

                            if (src.AssociatedFirm != null)

                                return "AssociatedFirm";

                            if (src.Review != null)

                                return "Review";

                            if (src.Schedule != null)

                                return "Schedule";

                            return "Participant";

                      })

                  );

                  //.ForMember(d => d.NoteParent, opt => opt.MapFrom(src => src.Agent ?? src.AssociatedFirm ?? src.Review ?? src.Schedule ?? src.Participant));

    }

}

​

public class Note

{

    public string Agent { get; set; }

    public string AssociatedFirm { get; set; }

    public string Review { get; set; }

    public string Schedule { get; set; }

    public string Participant { get; set; }

}

​

public class NoteVM

{

    public string NoteParent { get; set; }

}