在实体框架上创建外键关系的问题

Problems creating a Foreign-Key relationship on Entity Framework(在实体框架上创建外键关系的问题)

问题描述

我在我的 Entity Framework fluent Api 中配置外键关系时遇到问题:

i'm having trouble configuring a foreign key relationship in my Entity Framework fluent Api:

这是报告的主要内容:

 public class Testata
{
    public Testata() { Details = new List<Dettaglio>(); }
    public virtual int IDTEST { get; set; }
    public virtual string Value { get; set; }
    public virtual int IDDETAIL { get; set; }
    public virtual string IDTESTALT { get; set; }
    public virtual byte[] BLOB { get; set; }

    public virtual IList<Dettaglio> Details { get; set; }
}

这是报告的详细信息

public class Dettaglio
{
    public virtual int IDDETAIL { get; set; }
    public virtual int IDTEST { get; set; }
    public virtual string DSDETAIL { get; set; }

    public virtual Testata TEST_TABLE { get; set; }
}

这是我对两者的流畅 API 定义.报告负责人:

And this is my fluent API definition of both. Head of the report:

public TEST_TABLEMap()
    {
        // Primary Key
        this.HasKey(t => t.IDTEST)
            .Property(t => t.IDTEST)
            .IsRequired()
            .HasColumnType("Int")
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity)
            .HasColumnName("IDTEST");


        // Table & Column Mappings
        this.ToTable("TEST_TABLE");
        this.Property(t => t.Value).HasColumnName("DSVALUETEST");
        this.Property(t => t.IDTESTALT).HasColumnName("IDTESTALT");
        this.Property(t => t.BLOB).HasColumnName("BLOB");
    }

报告详情:

public TEST_DETAILMap()
    {
        // Primary Key
        this.HasKey(t => t.DSDETAIL);

        // Properties
        this.Property(t => t.DSDETAIL);

        // Table & Column Mappings
        this.ToTable("TEST_DETAIL");
        this.Property(t => t.IDDETAIL).HasColumnName("IDDETAIL");
        // this.Property(t => t.IDTEST).HasColumnName("IDTEST");
        this.Property(t => t.DSDETAIL).HasColumnName("DSDETAIL");

        // Relationships
        this.HasOptional(t => t.TEST_TABLE)
            .WithMany(t => t.Details)
            .HasForeignKey(d => d.IDDETAIL).WillCascadeOnDelete(true);

    }

在执行时我总是得到这个错误

On execution i always get this error

System.Data.Entity.Edm.EdmAssociationType: : 多重性与关系Dettaglio_TEST_TABLE"中角色Dettaglio_TEST_TABLE_Target"中的引用约束冲突.由于 Dependent Role 中的所有属性都不可为空，因此 Principal Role 的复数必须为1".

System.Data.Entity.Edm.EdmAssociationType: : Multiplicity conflicts with the referential constraint in Role 'Dettaglio_TEST_TABLE_Target' in relationship 'Dettaglio_TEST_TABLE'. Because all of the properties in the Dependent Role are non-nullable, multiplicity of the Principal Role must be '1'.

我猜这意味着我在外键定义方面失败了，但我真的不知道在哪里看.非常感谢任何帮助/提示.

Which, i guess, means i'm failing something at foreign key definition, but i don't really know where to look at. Any help/hint is much appreciated.

推荐答案

Dettaglio类中的外键属性冲突...

There is a conflict between your foreign key property in class Dettaglio...

public virtual int IDTEST { get; set; }

...它具有不可为空的类型 (int)，因此不能是可选的，您的映射...

...which has a non-nullable type (int) and therefore cannot be optional and your mapping...

this.HasOptional(t => t.TEST_TABLE) //...

...您希望关系是可选的.

...where you want the relationship to be optional.

如果您确实需要可选关系，请使用可为空的 FK 属性:

If you indeed want an optional relationship use a nullable FK property:

public virtual int? IDTEST { get; set; }

否则，您必须将 HasRequired 用于与不可为空的 FK 属性的必需关系.

Otherwise you must use HasRequired for a required relationship with a non-nullable FK property.

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