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entity framework支持2个实体间存在多个关系么?

0
[待解决问题]

简单来说,有两个table:

tblInvestment
{
InvestmentId char(10), --pk
PrimaryPerformanceId char(10)
}

tblPerformance
{
PerformanceId char(10), --pk,
InvestmentId char(10)
}

然后定义了2个实体类:

[Table("tblInvestment")]
class Investment
{
[Key]
public string InvestmentId { get; set; }
public string PrimaryPerformanceId { get; set; }

[ForeignKey("PrimaryPerformanceId")]
public virtual Performance PrimaryPerformance { get; set; }
[ForeignKey("InvestmentId")]
public virtual ICollection<Performance> Performances { get; set; }
}

[Table("tblPerformance")]
class Performance
{
[Key]
public string PerformanceId { get; set; }
public string InvestmentId { get; set; }
[ForeignKey("InvestmentId")]
public virtual Investment Investment { get; set; }
}

经测试,实体类没有问题,但是当调用DbContext的时候,会出现异常:“Unable to determine a valid ordering for dependent operations. Dependencies may exist due to foreign key constraints, model requirements, or store-generated values.

System.Data.Mapping.Update.Internal.UpdateTranslator.DependencyOrderingError(IEnumerable`1 remainder) System.Data.Mapping.Update.Internal.UpdateTranslator.ProduceCommands() System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter) System.Data.EntityClient.EntityAdapter.Update(IEntityStateManager entityCache) System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options) System.Data.Entity.Internal.InternalContext.SaveChanges() System.Data.Entity.Internal.InternalContext.SaveChanges() System.Data.Entity.Internal.LazyInternalContext.SaveChanges() System.Data.Entity.DbContext.SaveChanges()

 


FMax的主页 FMax | 菜鸟二级 | 园豆:205
提问于:2012-03-19 15:41
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所有回答(3)
0

你这里关系比较乱,是你在做测试还是项目中用到了,你的两个实体怎么会有这样的引用关系?

[ForeignKey("InvestmentId")]
public virtual ICollection<Performance> Performances { get; set; }
这里的标记也有问题吧?
artwl | 园豆:16536 (专家六级) | 2012-03-19 15:59

当然有这样的关系。比如说一个物品拍卖,可以有很多出价记录,但是只有一个竞标成功。

支持(0) 反对(0) FMax | 园豆:205 (菜鸟二级) | 2012-03-19 16:02
0

这个看着有点晕,还是用FluentAPI定义看起来直观。

建议根据你的实体配置,让EF生成数据库看看。

dudu | 园豆:37370 (高人七级) | 2012-03-19 16:06

这里有个blog:http://weblogs.asp.net/manavi/archive/2011/05/17/associations-in-ef-4-1-code-first-part-6-many-valued-associations.aspx,里面的例子跟我的有点类似:Item & Bid。

ER

支持(0) 反对(0) FMax | 园豆:205 (菜鸟二级) | 2012-03-19 16:09

@FMax: 能不能把与这个问题相关的代码发给我?

支持(0) 反对(0) dudu | 园豆:37370 (高人七级) | 2012-03-20 17:01
0

这种多个关系可以存在,但是你的 DataAnnotation 写得确实有问题,您原来的是这样的:

    [Table("tblInvestment")]
    public class Investment
    {
        [Key]
        public string InvestmentId { get; set; }
        public string PrimaryPerformanceId { get; set; }
        [ForeignKey("PrimaryPerformanceId")]
        public virtual Performance PrimaryPerformance { get; set; }
        [ForeignKey("InvestmentId")]//(1)
        public virtual ICollection<Performance> Performances { get; set; }
    }

    [Table("tblPerformance")]
    public class Performance
    {
        [Key]
        public string PerformanceId { get; set; }
        public string InvestmentId { get; set; }
        [ForeignKey("InvestmentId")]//(2)
        public virtual Investment Investment { get; set; }
    }

(1)和(2)应该描述的同一个外键,所以有点多余了,导致错误。

应该去掉其中一处,但是如果单纯去掉其中一处,EF还是会给tblPerformance生成两个外键,幸好EF提供了InverseProperty, 用以指定这种关系的另一端, 所以代码可以改成这样:

    [Table("tblInvestment")]
    public class Investment
    {
        [Key]
        public string InvestmentId { get; set; }
        public string PrimaryPerformanceId { get; set; }
        [ForeignKey("PrimaryPerformanceId")]
        public virtual Performance PrimaryPerformance { get; set; }
        [InverseProperty("Investment")]
        [ForeignKey("InvestmentId")]
        public virtual ICollection<Performance> Performances { get; set; }
    }

    [Table("tblPerformance")]
    public class Performance
    {
        [Key]
        public string PerformanceId { get; set; }
        public string InvestmentId { get; set; }
        //[InverseProperty("Performances")]
        //[ForeignKey("InvestmentId")]
        public virtual Investment Investment { get; set; }
    }

或者这样:

    [Table("tblInvestment")]
    public class Investment
    {
        [Key]
        public string InvestmentId { get; set; }
        public string PrimaryPerformanceId { get; set; }
        [ForeignKey("PrimaryPerformanceId")]
        public virtual Performance PrimaryPerformance { get; set; }
        //[InverseProperty("Investment")]
        //[ForeignKey("InvestmentId")]
        public virtual ICollection<Performance> Performances { get; set; }
    }

    [Table("tblPerformance")]
    public class Performance
    {
        [Key]
        public string PerformanceId { get; set; }
        public string InvestmentId { get; set; }
        [InverseProperty("Performances")]
        [ForeignKey("InvestmentId")]
        public virtual Investment Investment { get; set; }
    }
ChatinCode | 园豆:2272 (老鸟四级) | 2012-04-16 15:00

谢谢关注这个问题,不过问题确实不是由于这个造成的。

支持(0) 反对(0) FMax | 园豆:205 (菜鸟二级) | 2012-04-18 21:45

@FMax: Why, 您的实体类我测试过确实不行,我的测试代码是这样的:

            using (var context = new BlogContext())
            {
                context.Projects.Add(new Project { ProjectName = "TestProject", ID = Guid.NewGuid()});
                context.SaveChanges();
                var project = context.Projects.First();
                context.ProjectUsers.Add(new ProjectUser { Project = project, UserID= "#001"});
                context.SaveChanges();
            }
支持(0) 反对(0) ChatinCode | 园豆:2272 (老鸟四级) | 2012-04-20 08:09
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