有条件地将一种源类型映射到两种目标类型

Question

我有一个这样的源 DTO

public class Member 
{
    public string MemberId {get;set;}
    public string MemberType {get;set;}
    public string Name {get;set;}
}

成员类型可以是"Person"或"Company"。

还有两个目的地class是这样的

public class PersonMember 
{
    public int PersonMemberId {get;set;}
    public string Name {get;set;}
}

public class CompanyMember 
{
    public int CompanyMemberId {get;set;}
    public string Name {get;set;}
}

我想使用 Automapper 检查源中 MemberType 的值 class 并根据该类型映射到两个目标类型之一。

我看到了 conditionally mapping 的示例，但它映射了执行条件检查的字段。我想检查条件并映射不同的字段。

var config = new MapperConfiguration(cfg => {
  cfg.CreateMap<Foo,Bar>()
    .ForMember(dest => dest.baz, opt => opt.Condition(src => (src.baz >= 0))); 
});

我的目标是这样的 -

cfg.CreateMap<Member, PersonMember>()
.ForMember(dest => PersonMember.PersonMemberId, opt => if the source.MemberType == "Person" perform mapping from MemberId, otherwise do nothing);

cfg.CreateMap<Member, CompanyMember>()
.ForMember(dest => CompanyMember.CompanyMemberId, opt => if the source.MemberType == "Company" perform mapping from MemberId, otherwise do nothing);

Answer 1

使用自动映射器，您必须在调用映射器上指定 return 类型，例如。 mapper.Map<PersonMember>(member)，这表明 return 类型是 PersonMember 所以你不能 return CompanyMember.

你可以这样做：

var configPerson = new MapperConfiguration(cfg => cfg.CreateMap<Member, PersonMember>());
var configCompany = new MapperConfiguration(cfg => cfg.CreateMap<Member, CompanyMember>());

PersonMember personMember = null;
CompanyMember companyMember = null;

switch (member.MemberType )
{
    case "PersonMember":
        var mapper = configPerson.CreateMapper();
        personMember = mapper.Map<PersonMember>(member);
        break;
    case "CompanyMember":
        var mapper = configCompany.CreateMapper();
        companyMember = mapper.Map<CompanyMember>(member);
        break;
    default:
        throw new Exception("Unknown type");
        break;
}

或者您可以尝试 Custom type converters 和 object 作为 return 类型。

Answer 2

I saw the example of conditionally mapping, but it maps the field it performs the conditional check on. I want to check the condition and map a different field.

尝试使用这样的配置：

cfg.CreateMap<Member, PersonMember>()
    .ForMember(dest => PersonMember.PersonMemberId, opt => { 
        opt.Condition(src => src.MemberType == "Person");
        opt.MapFrom(src => src.MemberId);
     });
cfg.CreateMap<Member, CompanyMember>()
    .ForMember(dest => CompanyMember.CompanyMemberId, opt => { 
        opt.Condition(src => src.MemberType == "Company");
        opt.MapFrom(src => src.MemberId);
     });

如果您从不兼容的对象进行映射，Id 字段将设置为 0。

Answer 3

对于版本 5 及更高版本，您可以尝试以下代码：

using System;
using AutoMapper;

namespace AutoMapOneToMulti
{
    class Program
    {
        static void Main(string[] args)
        {
            RegisterMaps();

            var s = new Source { X = 1, Y = 2 };

            Console.WriteLine(s);
            Console.WriteLine(Mapper.Map<Source, Destination1>(s));
            Console.WriteLine(Mapper.Map<Source, Destination2>(s));

            Console.ReadLine();
        }
        static void RegisterMaps()
        {
            Mapper.Initialize(cfg => cfg.AddProfile<GeneralProfile>());
        }
    }
    public class GeneralProfile : Profile
    {
        public GeneralProfile()
        {
            CreateMap<Source, Destination1>();
            CreateMap<Source, Destination2>();
        }
    }
    public class Source
    {
        public int X { get; set; }

        public int Y { get; set; }

        public override string ToString()
        {
            return string.Format("Source = X : {0}, Y : {1}", X, Y);
        }
    }
    public class Destination1
    {
        public int X { get; set; }

        public int Y { get; set; }
        public override string ToString()
        {
            return string.Format("Destination1 = X : {0}, Y : {1}", X, Y);
        }
    }
    public class Destination2
    {
        public int X { get; set; }

        public int Y { get; set; }
        public override string ToString()
        {
            return string.Format("Destination2 = X : {0}, Y : {1}", X, Y);
        }
    }
}

对于低于 5 的版本，您可以试试这个：

using System;
using AutoMapper;

namespace AutoMapOneToMulti
{
    class Program
    {
        static void Main(string[] args)
        {
            RegisterMaps();

            var s = new Source { X = 1, Y = 2 };

            Console.WriteLine(s);
            Console.WriteLine(Mapper.Map<Source, Destination1>(s));
            Console.WriteLine(Mapper.Map<Source, Destination2>(s));

            Console.ReadLine();
        }
        static void RegisterMaps()
        {
            Mapper.Initialize(cfg => cfg.AddProfile<GeneralProfile>());
        }
    }
    public class GeneralProfile : Profile
    {
        protected override void Configure()
        {
            CreateMap<Source, Destination1>();
            CreateMap<Source, Destination2>();
        }
    }
    public class Source
    {
        public int X { get; set; }

        public int Y { get; set; }

        public override string ToString()
        {
            return string.Format("Source = X : {0}, Y : {1}", X, Y);
        }
    }
    public class Destination1
    {
        public int X { get; set; }

        public int Y { get; set; }
        public override string ToString()
        {
            return string.Format("Destination1 = X : {0}, Y : {1}", X, Y);
        }
    }
    public class Destination2
    {
        public int X { get; set; }

        public int Y { get; set; }
        public override string ToString()
        {
            return string.Format("Destination2 = X : {0}, Y : {1}", X, Y);
        }
    }
}

如果你想要一个动态函数，使用这个扩展：

public static dynamic DaynamicMap(this Source source)
{
    if (source.X == 1)
        return Mapper.Map<Destination1>(source);
    return Mapper.Map<Destination2>(source);
}

Console.WriteLine(new Source { X = 1, Y = 2 }.DaynamicMap());
Console.WriteLine(new Source { X = 2, Y = 2 }.DaynamicMap());

Answer 4

介绍一些基础classMember。从新基数 class.

继承 PersonMember, CompanyMember

然后定义这些映射：

cfg.CreateMap<Dto.Member, Member>()
    .ConstructUsing((memberDto, context) => {
    switch (memberDto.MemberType)
    {
        case "PersonMember":
            return context.Mapper.Map<PersonMember>(memberDto);
        case "CompanyMember":
            return context.Mapper.Map<CompanyMember>(memberDto);
        default:
            throw new ArgumentOutOfRangeException($"Unknown MemberType {memberDto.MemberType}");
    }
});

cfg.CreateMap<Dto.Member, PersonMember>()
    .ForMember(dest => PersonMember.PersonMemberId,
               opt => opt.MapFrom(src => src.MemberId));

cfg.CreateMap<Dto.Member, CompanyMember>()
    .ForMember(dest => CompanyMember.CompanyMemberId,
               opt => opt.MapFrom(src => src.MemberId));

现在您可以使用 _mapperInstance.Map<Member>(memberDto);

进行映射

有条件地将一种源类型映射到两种目标类型

Conditionally mapping one source type to two destination types

c#

mapping

automapper