Question

当我有两个这样的模型时：

public class PredictionGroup
{
    [Key]
    public Guid PredictionGroupId { get; set; }

    public Guid? ResultPredictionId { get; set; }

    [ForeignKey("ResultPredictionId")]
    public Prediction ResultPrediction { get; set; }

    public List<Prediction> Predictions { get; set; }
}

public class Prediction
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid PredictionId { get; set; }

    [Required]
    public Guid PredictionGroupId { get; set; }

    [ForeignKey("PredictionGroupId")]
    public PredictionGroup PredictionGroup { get; set; }
}

这将生成：

CreateTable(
    "Website.PredictionGroups",
    c => new
        {
            PredictionGroupId = c.Guid(nullable: false, identity: true),
            ResultPredictionId = c.Guid(),
        })
    .PrimaryKey(t => t.PredictionGroupId)
    .ForeignKey("Website.Predictions", t => t.ResultPredictionId)
    .Index(t => t.ResultPredictionId);

CreateTable(
    "Website.Predictions",
    c => new
        {
            PredictionId = c.Guid(nullable: false, identity: true),
            PredictionGroupId = c.Guid(nullable: false),
            PredictionGroup_PredictionGroupId = c.Guid(),
        })
    .PrimaryKey(t => t.PredictionId)
    .ForeignKey("Website.PredictionGroups", t => t.PredictionGroupId)
    .ForeignKey("Website.PredictionGroups", t => t.PredictionGroup_PredictionGroupId)
    .Index(t => t.PredictionGroupId)
    .Index(t => t.PredictionGroup_PredictionGroupId);

当我尝试在我的数据库中输入此内容时，我收到错误：Unable to determine the principal end of the 'Site.Data.Prediction_PredictionGroup' relationship. Multiple added entities may have the same primary key.

有人可以对此发光吗？

Answer 1

我添加了这个Fluent API代码：

        modelBuilder.Entity<PredictionGroup>()
            .HasOptional(m => m.ResultPrediction)
            .WithOptionalDependent()
            .Map(x => x.MapKey("PredictionResultGroupId"));

MapKey是可选的，但我希望只使用注释即可完成。

Answer 2

我不确定您的模型是否正确，这就是您需要添加Fluent API代码的原因。您不应该需要Fluent API代码。 [ForeignKey]定义在属性上进行，该属性是外键值，并指向它是键的对象。因此属性属性在ResultPredictionId上，并为属性ResultPrediction表示。目前它正好相反。

public class PredictionGroup
{
    [Key]
    public Guid PredictionGroupId { get; set; }

    [ForeignKey("ResultPrediction")] //this is the key, point it to the object
    public Guid? ResultPredictionId { get; set; }


    public Prediction ResultPrediction { get; set; }

    public List<Prediction> Predictions { get; set; }
}

public class Prediction
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid PredictionId { get; set; }

    [Required]
    [ForeignKey("PredictionGroup")]
    public Guid PredictionGroupId { get; set; }


    public PredictionGroup PredictionGroup { get; set; }
}

可选的一对一关系

2 个答案: