using System;

using AutoMapper;

public class Program

{

    public static void Main()

    {

        var configuration = new MapperConfiguration(cfg => {

            cfg.CreateMap<ReadingModel, HistoryCreateModel>()

                .ForMember(dest => dest.Value, _ => _.MapFrom<HealthMeasurementValueResolver>()) // i get 97, that's spo2 Value

                //.ForMember(dest => dest.Value, _ => _.MapFrom(src => (float) src.Spo2)) // i get 83, that's pulse value

                .ForAllOtherMembers(_ => _.Ignore());

            cfg.CreateMap<ReadingModel, HealthDataHistoryPulseCreateModel>()

                .IncludeBase<ReadingModel, HistoryCreateModel>()

                .ForMember(dest => dest.Value, _ => _.MapFrom(src => (float) src.Pulse));

        });

​

        IMapper mapper = configuration.CreateMapper();

​

        var readingModel = new ReadingModel {

            Spo2 = 97,

            Pulse = 83,

            Type = "spo2"

        };

        var result = mapper.Map<ReadingModel, HealthDataHistoryPulseCreateModel>(readingModel);

        Console.WriteLine(result.Value);

    }

}

​

public class HealthMeasurementValueResolver : IValueResolver<ReadingModel, object, float>

{

    public float Resolve(ReadingModel source, object destination, float destMember, ResolutionContext context)

    {

        return source.Type switch

        {

            "spo2" => (float) source.Spo2,

            _ => 0

        };

    }

}

​

// models 

public class ReadingModel

{

    public string Type { get; set; }

    public float? Spo2 { get; set; }

    public float? Pulse { get; set; }

}

​

public class HistoryCreateModel

{

    public int UserId { get; set; }

    public float Value { get; set; }

}

​

public class HealthDataHistoryPulseCreateModel : HistoryCreateModel { }