自动映射器 - 根据映射的对象类型设置值

这是我的DTO：

public class DiaryEventType_dto
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public string  Group { get; set; }
    public bool Redundant { get; set; }
    public string Type { get; set; }
}

它映射到两种可能的实体类型：

public partial class UserDiaryEventType
{
    public System.Guid Id { get; set; }
    public string Name { get; set; }
    public string TypeGroup { get; set; }
    public bool Redundant { get; set; }
}
public partial class SystemDiaryEventType
{
    public System.Guid Id { get; set; }
    public string Name { get; set; }
    public string TypeGroup { get; set; }
    public bool Redundant { get; set; }
}

"Type"属性旨在区分DTO最初映射的类型（为什么我要这样做而不是有两个单独的DTO类？遗留代码，这就是为什么 - 太痛苦而无法改变这一切）。

理想情况下，我想在自动映射期间填充它，否则映射器会向我抛出一个摇摆不定的人，因为"类型"没有映射：

        Mapper.CreateMap<Entities.UserDiaryEventType, DiaryEventType_dto>()
            .ForMember(m => m.Group, o => o.MapFrom(s => s.TypeGroup));
        Mapper.CreateMap<DiaryEventType_dto, Entities.UserDiaryEventType>()
            .ForMember(m => m.TypeGroup, o => o.MapFrom(s => s.Group));
        Mapper.CreateMap<Entities.SystemDiaryEventType, DiaryEventType_dto>()
            .ForMember(m => m.Group, o => o.MapFrom(s => s.TypeGroup));
        Mapper.CreateMap<DiaryEventType_dto, Entities.SystemDiaryEventType>()
            .ForMember(m => m.TypeGroup, o => o.MapFrom(s => s.Group));

但是我无法弄清楚这样做的语法。像这样：

//pseudo code
Mapper.CreateMap<DiaryEventType_dto, Entities.UserDiaryEventType>()
     .SetValue("User");
Mapper.CreateMap<DiaryEventType_dto, Entities.SystemDiaryEventType>()
     .SetValue("System");

可能吗？

Mapper.CreateMap<Entities.UserDiaryEventType, DiaryEventType_dto>()
        .ForMember(m => m.Group, o => o.MapFrom(s => s.TypeGroup))
        .ForMember(m => m.Group, o => o.ResolveUsing(s => "User"));