我试图在公共(public)基类和不相关类的派生类之间创建 2 个一对一的关系，这样当我删除父行时，数据库中的子行也会被删除。
几天来我一直在思考这个问题，并且我已经尝试了 fluent api 中所有(对我来说)可以想象的关系组合。至今没有任何令人满意的结果。这是我的设置:

public class OtherType
{
 public int ID {get; set;}

 public int? DerivedTypeAID {get; set;}
 public virtual DerivedTypeA DerivedType {get; set;}

 public int? DerivedTypeBID {get; set;}
 public virtual DerivedTypeB DerivedType {get; set;}
}


public abstract class BaseType
{
  public int ID {get; set;}
  public string ClassName {get; set;}
  public virtual OtherType {get; set;}
}


public class DerivedTypeA : BaseType
{
 public string DerivedProperty {get; set;}
}

public class DerivedTypeB : BaseType
{
 public string DerivedProperty {get; set;}
}

public class MyContext : DbContext
{
 public MyContext()
        : base("name=MyContext")
    {
    }

    public DbSet<OtherType> OtherTypes { get; set; }
    public DbSet<BaseType> BaseTypes { get; set; }



    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        var m = modelBuilder;

        m.Entity<OtherType>().HasOptional(_ => _.DerivedTypeA)
            .WithMany().HasForeignKey(_ => _.DerivedTypeAID).WillCascadeOnDelete(true);
        m.Entity<OtherType>().HasOptional(_ => _.DerivedTypeB)
            .WithMany().HasForeignKey(_ => _.DerivedTypeBID).WillCascadeOnDelete(true);

        m.Entity<DerivedTypeA>().HasRequired(_ => _.OtherType).WithMany().HasForeignKey(_ => _.ID).WillCascadeOnDelete(true);
        m.Entity<DerivedTypeB>().HasRequired(_ => _.OtherType).WithMany().HasForeignKey(_ => _.ID).WillCascadeOnDelete(true);
    }
}

public abstract class BaseType
{
    public int BaseTypeId { get; set; }
}

public class DerivedTypeA : BaseType
{
    public virtual OtherType OtherType { get; set; }
}

public class DerivedTypeB : BaseType
{
    public virtual OtherType OtherType { get; set; }
}

public class OtherType
{
    public int Id { get; set; }

    public virtual DerivedTypeA DerivedTypeA { get; set; }

    public virtual DerivedTypeB DerivedTypeB { get; set; }
}

public class TPCModel : DbContext
{

    public TPCModel()
        : base("name=TPCModel")
    {

    }

    public DbSet<BaseType> BaseTypes { get; set; }
    public DbSet<OtherType> OtherTypes { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        var m = modelBuilder;

        m.Entity<BaseType>().Property(_ => _.BaseTypeId)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

        m.Entity<DerivedTypeA>().Map(x =>
            {
                x.MapInheritedProperties();
                x.ToTable("DerivedTypeA");
            });

        m.Entity<DerivedTypeB>().Map(x =>
            {
                x.MapInheritedProperties();
                x.ToTable("DerivedTypeB");
            });

        m.Entity<DerivedTypeA>().HasRequired(_ => _.OtherType)
            .WithOptional(_ => _.DerivedTypeA).WillCascadeOnDelete(true);

        m.Entity<DerivedTypeB>().HasRequired(_ => _.OtherType)
            .WithOptional(_ => _.DerivedTypeB).WillCascadeOnDelete(true);

    }


}

using (var ctx = new TPCModel())
{
    Database.SetInitializer(new DropCreateDatabaseAlways<TPCModel>());
     ctx.Database.Initialize(true);

    ctx.OtherTypes.Add(new OtherType()
    {
        DerivedTypeA = new DerivedTypeA() { BaseTypeId=1 },
        DerivedTypeB = new DerivedTypeB() { BaseTypeId=2 }
    });

    ctx.SaveChanges(); // Exception throws here
}

Additional information: The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message: Saving or accepting changes failed because more than one entity of type 'EF6.CodeFirst.TPC.Model.SecondConcreteType' have the same primary key value. Ensure that explicitly set primary key values are unique. Ensure that database-generated primary keys are configured correctly in the database and in the Entity Framework model. Use the Entity Designer for Database First/Model First configuration. Use the 'HasDatabaseGeneratedOption" fluent API or 'DatabaseGeneratedAttribute' for Code First configuration.

最佳答案

我认为您的问题与 OtherType 类中导航属性的类型有关。

我认为在这种情况下您不能拥有强类型属性。

这在您的模型所暗示的循环级联删除中具有根本原因。

作为第二个解决方法，因为您已经找到了，请尝试以下我在类似场景中使用的模型:(Person = OtherType，PersonDetail = BaseType，HumanBeing = DerivedTypeA，Corporation = DerivedTypeB)

public class Person
{
    public Guid Id { get; set; }

    public string Designation { get; set; }

    public virtual PersonDetail Detail { get; set; }

    public virtual Person AggregatedOn { get; set; }

    protected ICollection<Person> aggregationOf;
    public virtual ICollection<Person> AggregationOf
    {
        get { return aggregationOf ?? (aggregationOf = new HashSet<Person>()); }
        set { aggregationOf = value; }
    }
}

public abstract class PersonDetail
{
    public Guid Id { get; set; }

    public virtual Person Personne { get; set; }
}

public class Corporation : PersonDetail
{
    public string Label { get; set; }
}

public class HumanBeing : PersonDetail
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class ReferentialContext : DbContext
{
    public ReferentialContext()
        : base("ReferentialContext")
    {
    }

    public ReferentialContext(string nameOrConnectionString)
        : base(nameOrConnectionString)
    {
    }

    public DbSet<Person> Personnes { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Types().Configure(t => t.ToTable(t.ClrType.Name.ToUpper()));
        modelBuilder.Properties().Configure(p => p.HasColumnName(p.ClrPropertyInfo.Name.ToUpper()));

        modelBuilder.Configurations.Add(new PersonConfiguration());
        modelBuilder.Configurations.Add(new PersonDetailConfiguration());

    }
}

class PersonConfiguration : EntityTypeConfiguration<Person>
{
    public PersonConfiguration()
    {
        this.HasMany(p => p.AggregationOf)
            .WithOptional(p => p.AggregatedOn);
    }
}

class PersonDetailConfiguration : EntityTypeConfiguration<PersonDetail>
{
    public PersonDetailConfiguration()
    {
        this.Property(p => p.Id)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

        this.HasRequired(p => p.Personne)
            .WithRequiredDependent(p => p.Detail);
    }
}

关于c# - Entity Framework 6.1 Code First Cascading Delete with TPH 用于派生类型上的一对一关系，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23205731/