AutoMapper：使用“忽略”在两个集合之间进行映射

Question

我正在使用 AutoMapper 在两个集合之间进行映射。我看到的是选项Ignore 在这种情况下没有按预期工作。我所期待的可以在方法AutoMapperIgnore_TwoObjectMappedWithIgnoreId_SameWithUnchangedIdAndNewPrice() 中看到。在其他两种测试方法中，Id 虽然被忽略了，但集合中的每个对象都会再次创建，其后果是原始值将丢失。有可能使用UseDestinationValue，但我认为这只对集合是它的成员的类有意义。如何在集合上使用选项Ignore？

[TestClass]
public class AutoMapperTests
{
    private readonly IEnumerable<Dto> _testDtos;

    private readonly IEnumerable<Entity> _testEntities;

    public AutoMapperTests()
    {
        _testDtos = new List<Dto>
        {
            new Dto()
            {
                Id = 0,
                Fk_Id = 8,
                Price = 350000
            }
        };


        _testEntities = new List<Entity>
        {
            new Entity()
            {
                Id = 8,
                Price = 68000
            }
            ,
            new Entity()
            {
                Id = 6,
                Price = 350000
            }
        };
    }

    [TestInitialize]
    public void TestInitialize()
    {
        Mapper.Reset();
    }

    [TestMethod]
    public void AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntityIgnoreId_SameWithUnchangedIdAndNewPrice()
    {
        //Assign
        Mapper.CreateMap<Dto, Entity>()
            .ForMember(destination => destination.Id, opt => opt.Ignore());

        AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntity_SameWithUnchangedIdAndNewPrice(true);
    }

    [TestMethod]
    public void AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntityUseDestinationtValueForId_SameWithUnchangedIdAndNewPrice()
    {
        //Assign
        Mapper.CreateMap<Dto, Entity>()
            .ForMember(destination => destination.Id, opt => opt.UseDestinationValue());

        AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntity_SameWithUnchangedIdAndNewPrice(true);
    }


    private void AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntity_SameWithUnchangedIdAndNewPrice(bool isExceptedSame)
    {
        //Assign
        var exceptedPrice = _testDtos.First().Price;

        //Act
        IEnumerable<Entity> foundEntities = _testEntities.Join(_testDtos, e => e.Id, e => e.Fk_Id, (entity, dto) => entity).ToList();
        Entity entityBeforeMapping = foundEntities.First();

        Mapper.Map(_testDtos, foundEntities);

        Entity entityAfterMapping = foundEntities.First();


        //Assert
        if (isExceptedSame)
        {
            Assert.AreSame(entityBeforeMapping, entityAfterMapping);
        }
        Assert.AreEqual(entityBeforeMapping.Id, entityAfterMapping.Id);
        Assert.AreEqual(exceptedPrice, entityAfterMapping.Price);
    }

    [TestMethod]
    public void AutoMapperIgnore_TwoObjectMappedWithIgnoreId_SameWithUnchangedIdAndNewPrice()
    {
        //Assign
        Mapper.CreateMap<Dto, Entity>()
            .ForMember(destination => destination.Id, opt => opt.Ignore());

        var testDto = new Dto()
        {
            Id = 0,
            Fk_Id = 8,
            Price = 350000
        };

        var testEntity = new Entity()
        {
            Id = 8,
            Price = 68000
        };

        var exceptedPrice = testDto.Price;


        //Act
        Entity entityBeforeMapping = testEntity;
        Mapper.Map(testDto, testEntity);
        Entity entityAfterMapping = testEntity;


        //Assert
        Assert.AreSame(entityBeforeMapping, entityAfterMapping);
        Assert.AreEqual(entityBeforeMapping.Id, entityAfterMapping.Id);
        Assert.AreEqual(exceptedPrice, entityAfterMapping.Price);
    }

    internal class Dto
    {
        public int Id { get; set; }
        public int Fk_Id { get; set; }
        public Single? Price { get; set; }
    }

    internal class Entity
    {
        public int Id { get; set; }
        public Single? Price { get; set; }
    }
}

Answer 1

正如@Stef 提到的，您必须单独映射集合中的每个条目，像这样

_testEntities.Join(_testDtos, e => e.Id, e => e.Fk_Id, (entity, dto) => Mapper.Map(dto,entity));

这里是完整的功能示例：

[TestClass]
public class AutoMapperTests
{
    private readonly IEnumerable<Dto> _testDtos;

    private readonly IEnumerable<Entity> _testEntities;

    public AutoMapperTests()
    {
        _testDtos = new List<Dto>
        {
            new Dto()
            {
                Id = 0,
                Fk_Id = 8,
                Price = 350000
            }
        };


        _testEntities = new List<Entity>
        {
            new Entity()
            {
                Id = 8,
                Price = 68000
            }
            ,
            new Entity()
            {
                Id = 6,
                Price = 350000
            }
        };
    }

    [TestInitialize]
    public void TestInitialize()
    {
        Mapper.Reset();
    }

    [TestMethod]
    public void AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntityIgnoreId_SameWithUnchangedIdAndNewPrice()
    {
        //Assign
        Mapper.CreateMap<Dto, Entity>()
            .ForMember(destination => destination.Id, opt => opt.Ignore());

        AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntity_SameWithUnchangedIdAndNewPrice(true);
    }

    [TestMethod]
    public void AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntityUseDestinationtValueForId_SameWithUnchangedIdAndNewPrice()
    {
        //Assign
        Mapper.CreateMap<Dto, Entity>()
            .ForMember(destination => destination.Id, opt => opt.UseDestinationValue());


        AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntity_SameWithUnchangedIdAndNewPrice(true);
    }

    private void AutoMapperIgnore_TwoCollectionsWithOneCommonElementMappedFromDtoToEntity_SameWithUnchangedIdAndNewPrice(bool isExceptedSame)
    {
        //Assign
        var exceptedPrice = _testDtos.First().Price;

        //Act
        Entity entityBeforeMapping = _testEntities.First(testEntity => testEntity.Id == _testEntities.First().Id);
        IEnumerable<Entity> foundEntities = _testEntities.Join(_testDtos, e => e.Id, e => e.Fk_Id, (entity, dto) => Mapper.Map(dto,entity));
        Entity entityAfterMapping = foundEntities.First();


        //Assert
        if (isExceptedSame)
        {
            Assert.AreSame(entityBeforeMapping, entityAfterMapping);
        }
        Assert.AreEqual(entityBeforeMapping.Id, entityAfterMapping.Id);
        Assert.AreEqual(exceptedPrice, entityAfterMapping.Price);
    }

    [TestMethod]
    public void AutoMapperIgnore_TwoObjectMappedWithIgnoreId_SameWithUnchangedIdAndNewPrice()
    {
        //Assign
        Mapper.CreateMap<Dto, Entity>()
            .ForMember(destination => destination.Id, opt => opt.Ignore());

        var testDto = new Dto()
        {
            Id = 0,
            Fk_Id = 8,
            Price = 350000
        };

        var testEntity = new Entity()
        {
            Id = 8,
            Price = 68000
        };

        var exceptedPrice = testDto.Price;


        //Act
        Entity entityBeforeMapping = testEntity;
        Mapper.Map(testDto, testEntity);
        Entity entityAfterMapping = testEntity;


        //Assert
        Assert.AreSame(entityBeforeMapping, entityAfterMapping);
        Assert.AreEqual(entityBeforeMapping.Id, entityAfterMapping.Id);
        Assert.AreEqual(exceptedPrice, entityAfterMapping.Price);
    }

    internal class Dto
    {
        public int Id { get; set; }
        public int Fk_Id { get; set; }
        public Single? Price { get; set; }
    }

    internal class Entity
    {
        public int Id { get; set; }
        public Single? Price { get; set; }
    }
}

Answer 2

我做了一些测试并确认了您的问题。

当一个 IEnumerable 列表被映射时，AutoMapper 会创建一个新的 IEnumerable 列表，它只包含您定义要映射的属性，因此只有“价格”。

为了将 Dto 映射到实体，您需要定义一个属性，使它们成为唯一的，例如 PrimaryKey。

class Dto
{
    public long PrimaryKey { get; set; }
    public int Id { get; set; }
    public int Fk_Id { get; set; }
    public Single? Price { get; set; }
}

class Entity
{
    public long PrimaryKey { get; set; }
    public int Id { get; set; }

    public Single? Price { get; set; }
}

将列表映射到列表可以这样完成：

// Update entities in original list
foreach (var d in _testDtos)
{
    foreach (var e in _testEntities)
    {
        if (e.PrimaryKey == d.PrimaryKey)
        {
            Mapper.Map(d, e);
        }
    }
}

或者更友好的 linq：

// Create a new list
var foundEntities = _testEntities.Join(_testDtos, e => e.PrimaryKey, d => d.PrimaryKey, (entity, dto) => Mapper.Map<Entity>(dto)).ToList();