Question

我有一个Fixture模型：

public partial class Fixture
{
    public int FixtureId { get; set; }
    public string Season { get; set; }
    public byte Week { get; set; }

    //foreign key
    public int AwayTeamId { get; set; }
    //navigation properties
    public virtual Team AwayTeam { get; set; }

    //foreign key
    public int HomeTeamId { get; set; }
    //navigation properties
    public virtual Team HomeTeam { get; set; }

    public byte? AwayTeamScore { get; set; }
    public byte? HomeTeamScore { get; set; }
}

还有一个Fixture DTO：

public class FixtureDTO
{
    public int Id { get; set; }
    public string Season { get; set; }
    public byte Week { get; set; }
    public string AwayTeamName { get; set; }
    public string HomeTeamName { get; set; }
    public byte? AwayTeamScore { get; set; }
    public byte? HomeTeamScore { get; set; }
}

我正在使用AutoMapper进行映射，这是我第一次尝试使用它。这是我的映射：

CreateMap<Fixture, FixtureDTO>()
            .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.FixtureId))
            .ForMember(dest => dest.AwayTeamName, opt => opt.MapFrom(src => src.AwayTeam.TeamName))
            .ForMember(dest => dest.HomeTeamName, opt => opt.MapFrom(src => src.HomeTeam.TeamName));
        CreateMap<FixtureDTO, Fixture>();

它可以很好地获取Fixture并将其映射到我用来显示数据的FixtureDTO。但是当我想更新数据并将FixtureDTO传回来将其映射回Fixture时，我收到了一个错误。

public HttpResponseMessage PutFixture(int id, FixtureDTO fixture)
    {
        if (ModelState.IsValid && id == fixture.Id)
        {
            //do mapping manually here?

            var updated = _repository.UpdateFixture(Mapper.Map<Fixture>(fixture));
            return Request.CreateResponse(updated ? HttpStatusCode.OK : HttpStatusCode.NotFound);
        }
        return Request.CreateResponse(HttpStatusCode.BadRequest);
    }

这是我得到的错误：

Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.

有人可以帮忙吗？

编辑：反向映射：

CreateMap<Fixture, FixtureDTO>()
            .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.FixtureId))
            .ForMember(dest => dest.AwayTeamName, opt => opt.MapFrom(src => src.AwayTeam.TeamName))
            .ForMember(dest => dest.HomeTeamName, opt => opt.MapFrom(src => src.HomeTeam.TeamName));
        CreateMap<FixtureDTO, Fixture>()
            .ForMember(dest => dest.FixtureId, opt => opt.MapFrom(src => src.Id))
            .ForMember(dest => dest.AwayTeam.TeamName, opt => opt.MapFrom(src => src.AwayTeamName))
            .ForMember(dest => dest.HomeTeam.TeamName, opt => opt.MapFrom(src => src.HomeTeamName));

Answer 1

通常，EF在检测到以下情况之一时抛出异常：

Opimistic Concurrency Violation ：这通常发生在您尝试编辑的实体被修改时，否则在您加载，编辑和保存它的时间。（见：Entity Framework: "Store update, insert, or delete statement affected an unexpected number of rows (0)."）

错误设置ID ：没有为Pks或FK设置ID。当我错误地将Entity的FK设置为一个值并将关联的对象设置为具有不同ID的对象时，我也看到了这样的异常。

由于存储库中的某些代码，很可能会抛出此异常。如果您在存储库中发布代码，我们可能会更好地了解导致异常的原因。

Answer 2

首先，您需要创建从DTO到实体的反向映射（如果需要，提供自定义成员映射）：

Mapper.CreateMap<FixtureDTO, Fixture>();

第二 - 检索，映射和更新现有实体

if (ModelState.IsValid && id == fixture.Id)
{
    Fixture entity = _repository.FindById(fixture.Id);
    Mapper.Map(fixture, entity); // Use this mapping method!
    var updated = _repository.UpdateFixture(entity);
    // etc
}

Answer 3

扩展到@ lazyberezovsky的答案：

这是您可能需要的反向映射的（未经测试）示例：

CreateMap<FixtureDTO, Fixture>()
        .ForMember(dest => dest.FixtureId,
                   opt => opt.MapFrom(src => src.Id))
        .ForMember(dest => dest.AwayTeam,
                   opt => opt.MapFrom(src => new Team
                                                 {
                                                     TeamName = src.AwayTeamName
                                                 }))
        .ForMember(dest => dest.HomeTeam,
                   opt => opt.MapFrom(src => new Team
                                                 {
                                                     TeamName = src.HomeTeamName
                                                 }));

我过去使用过这种格式并且工作正常，但您也可以为团队创建特定的映射。例如：

CreateMap<string, Team>()....

另外，我假设您正在这样做，但断言您的配置有效。例如：

[Test]
public void AutoMapper_Configuration_IsValid()
{
    Mapper.Initialize(m => m.AddProfile<MyProfile>());
    Mapper.AssertConfigurationIsValid();
}

使用AutoMapper将DTO映射回模型

3 个答案: