我有一个配置，该配置会进行反向映射以将源对象展开为目标对象，但是，如果源对象属性是只读的，它将被自动忽略，因此我必须手动映射它。

我的某些源对象最多包含100个字段，像这样创建手动映射会很麻烦，而且我不确定为什么自动映射器中会存在这种行为。

有关我正在描述的工作示例，请参见下面的代码片段。

using System;
using AutoMapper;

namespace automappertests
{
    class Source
    {
        public int Field1Suffix1 { get; set; }
        public int Field1Suffix2 { get; set; }
        public int Field2Suffix1 { get; set; }

        // !!Attention!!
        // This is a readonly property with a private setter
        public int Field2Suffix2 => Field2Suffix1; 
    }

    class Destination
    {
        public Wrapper Field1 { get; set; }
        public Wrapper Field2 { get; set; }
    }

    class Wrapper
    {
        public int Suffix1 { get; set; }
        public int Suffix2 { get; set; }

        public static Wrapper New(int suffix1,int suffix2) =>
            new Wrapper
            {
                Suffix1 = suffix1,Suffix2 = suffix2
            };
    }

    class DestinationProfile : Profile
    {
        public DestinationProfile()
        {
            CreateMap<Destination,Source>()
                .ReverseMap()
                // !!Attention!!
                // Why do I need to have an explicit ForMember MapFrom for the readonly property?
                .ForMember(m => m.Field2,o => o.MapFrom(src => Wrapper.New(src.Field2Suffix1,src.Field2Suffix2)));
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var config = new MapperConfiguration(cfg => { cfg.AddProfile<DestinationProfile>(); });
            var mapper = config.CreateMapper();
            var source = new Source()
            {
                Field1Suffix1 = 1,Field1Suffix2 = 2,Field2Suffix1 = 3,};
            var destination = mapper.Map<Source,Destination>(source);
            Console.WriteLine($"Field1.Suffix1 = {destination.Field1.Suffix1}");
            Console.WriteLine($"Field1.Suffix2 = {destination.Field1.Suffix2}");
            Console.WriteLine($"Field2.Suffix1 = {destination.Field2.Suffix1}");
            Console.WriteLine($"Field2.Suffix2 = {destination.Field2.Suffix2}");
            Console.WriteLine("Press any key to continue.");
            Console.ReadKey();
        }
    }
}

Output without .ForMember:
Field1.Suffix1 = 1
Field1.Suffix2 = 2
Field2.Suffix1 = 3
Field2.Suffix2 = 0

Output with .ForMember:
Field1.Suffix1 = 1
Field1.Suffix2 = 2
Field2.Suffix1 = 3
Field2.Suffix2 = 3