Automapper - 多对象源和一个目标

Question

我使用自动映射器来映射多个对象(db类到ui对象).

地图1:

Mapper.CreateMap<sourceone, destination>().ForMember(sss => sss.one, m => m.MapFrom(source => source.abc));

地图2:

Mapper.CreateMap<sourcetwo, destination>().ForMember(sss => sss.two, m => m.MapFrom(source => source.xyz));

destination d = new destination();

//地图1

d = AutoMapper.Mapper.Map<sourceone, destination>(sourceone);

//地图2

d = AutoMapper.Mapper.Map<sourcetwo, destination>(sourcetwo);

一旦我调用'Map 2',使用Map 1填充的值就会丢失..(即destination.one变空).我该如何解决？

Answer 1

Map 有一个带有源和目标对象的重载:

d = AutoMapper.Mapper.Map<sourceone, destination>(sourceone);

/* Pass the created destination to the second map call: */
AutoMapper.Mapper.Map<sourcetwo, destination>(sourcetwo, d);

Answer 2

mapper.MergeInto<PersonCar>(person, car)

接受的答案为扩展方法,简单和通用版本:

public static TResult MergeInto<TResult>(this IMapper mapper, object item1, object item2)
{
    return mapper.Map(item2, mapper.Map<TResult>(item1));
}

public static TResult MergeInto<TResult>(this IMapper mapper, params object[] objects)
{
    var res = mapper.Map<TResult>(objects.First());
    return objects.Skip(1).Aggregate(res, (r, obj) => mapper.Map(obj, r));
}

在为每个输入类型配置映射之后:

IMapper mapper = new MapperConfiguration(cfg =>
{
    cfg.CreateMap<Person, PersonCar>();
    cfg.CreateMap<Car, PersonCar>();
}).CreateMapper();

Answer 3

只是想补充一点，现在您可以使用元组语法来定义多种类型的映射。

// configuring
Mapper
  .CreateMap<(SourceType1 Source1, SourceType2 Source2), DestinationType>()
    .ForMember(sss => sss.one, m => m.MapFrom(source => source.Source1.abc))
    .ForMember(sss => sss.two, m => m.MapFrom(source => source.Source2.xyz));

// using
var result = Mapper.Map<DestinationType>((source1, source2));

优点：

• 从第一种类型映射后不必记住从第二种类型映射
• 所有映射都在一个地方同时定义（只要您不需要单独的映射以及组合的映射）
• 当从超过 2 个源类型映射时，不再那么麻烦
• 本质上是@asidis的想法，但不需要单独的类型

缺点：

• 好吧，与一般的 Automapper 一样，您必须知道去哪里寻找，找出用于映射的类型
• 当涉及多种类型时可能看起来有点笨拙

Answer 4

public class Person
{
    public string Name { get; set; }
    public string PhNo { get; set; }
}
public class Company
{
    public int EmpNo { get; set; }
    public string Title { get; set; }
}

public class PersonCompany
{
    public string Name { get; set; }
    public string PhNo { get; set; }

    public int EmpNo { get; set; }
    public string Title { get; set; }
}

//you can test as below
        var pMap = Mapper.CreateMap<Person,PersonCompany>();
        pMap.ForAllMembers(d => d.Ignore()); 
        pMap.ForMember(d => d.Name, opt => opt.MapFrom(s => s.Name))
            .ForMember(d => d.PhNo, opt => opt.MapFrom(s => s.PhNo));

        var cMap = Mapper.CreateMap<Company, PersonCompany>();
        cMap.ForAllMembers(d => d.Ignore());
        cMap.ForMember(d => d.EmpNo, opt => opt.MapFrom(s => s.EmpNo))
            .ForMember(d => d.Title, opt => opt.MapFrom(s => s.Title));


        var person = new Person { Name = "PersonName", PhNo = "212-000-0000" };
        var personCompany = Mapper.Map<Person,PersonCompany>(person);
        var company = new Company { Title = "Associate Director", EmpNo = 10001 };
        personCompany = Mapper.Map(company, personCompany);

        Console.WriteLine("personCompany.Name={0}", personCompany.Name);
        Console.WriteLine("personCompany.PhNo={0}", personCompany.PhNo);
        Console.WriteLine("personCompany.EmpNo={0}", personCompany.EmpNo);
        Console.WriteLine("personCompany.Title={0}", personCompany.Title);

Answer 5

根据我的说法，您应该避免使用目标对象的实例调用重载的 Map 方法，如已接受的答案中所述。这不会让您测试/验证您的映射配置 ( Mapper.Configuration.AssertConfigurationIsValid())，否则您将在映射中添加大量“忽略”。

一个非常简单的解决方案是创建一个包含源引用的复合类型，并根据该复合类型定义到目标的映射。

就像是：

    public class SourceOneTwo
    {
        public SourceOne SourceOne { get; set; }
        public SourceTwo SourceTwo { get; set; }
    }
    static void Main(string[] args)
    {
        var config = new MapperConfiguration(cfg => 
            cfg.CreateMap<SourceOneTwo, Destination>()
            .ForMember(dest => dest.one, m => m.MapFrom(source => source.SourceOne.abc))
            .ForMember(dest => dest.two, m => m.MapFrom(source => source.SourceTwo.xyz)));
        config.AssertConfigurationIsValid();
    }

Answer 6

现在看来是这样的：

DestinationDto = _mapper.Map(source2, _mapper.Map<source1type, destinationType>(source1));