實體框架6.1：派生類型和標識關係中的1-1和1-many關係

Question

更新：我應該注意到NavigationPropertyClass上的Id屬性不是數據庫生成的。在我的實際模型中，NavigationPropertyClass也是層次結構方案（使用TPH）的一部分，此處未顯示，而NavigationPropertyClass有DerivedClass1實例和DerivedClass2實例的集合，但並非所有類都必須從基類從NavigationPropertyClass派生。

---

我的模型的一部分看起來像這樣（其他屬性和構造函數爲簡潔起見省略）：

//Many other classes inherit from this class 
//and many of the derived classes are not composed of DerivedClass1 or DerivedClass2 
public abstract SomeOtherBaseClass{ 
    public int Id {get; set;} //not database generated, set in the constructor 
} 

public NavigationPropertyClass: SomeOtherBaseClass{ 
    public DerivedClass1 Derived1 {get; set;} 
    public virtual ICollection<DerivedClass2> Derived2Collection {get; set;} 
} 

public abstract class BaseClass{ 
    public int Id {get; set;} 
    //other properties shared by derived classes 
} 

public class DerivedClass1: BaseClass{ 
    public NavigationPropertyClass NavigationProperty {get; set;} 
    //other properties pertinent to DerivedClass1 
} 


public class DerivedClass2: BaseClass{ 
    public NavigationPropertyClass NavigationProperty {get; set;} 
    //other properties pertinent to DerivedClass2 
} 

DerivedClass1具有NavigationPropertyClass 1-1關係，同時DerivedClass2具有許多-1與NavigationPropertyClass的關係。

我試圖在每個派生類中設置標識關係，以便當NavigationPropertyClass的實例從數據庫中刪除時，DerivedClass1的相關實例以及DerivedClass2的任何實例也將被刪除。我可以看到設置的唯一方法是使用TPT繼承，但即便如此，我也無法使事情正常工作。我會發布我的Fluent API配置，但我在這一點上嘗試了很多排列，我不知道應該發佈哪一個。

有沒有辦法做我想做的事情？如果是這樣，Fluent API配置是什麼樣的？

Answer 1

這是適合您的要求的型號。

public abstract class Base 
{ 
    public int Id { get; set; } 
} 
public class Derived1 : Base 
{ 
    public int PropDerived1 { get; set; } 
    public NavigationPropertyClass NavigationProperty { get; set; } 
} 
public class Derived2 : Base 
{ 
    public int PropDerived2 { get; set; } 

    public int NavigationPropertyClassId { get; set; } 
    public NavigationPropertyClass NavigationPropertyClass { get; set; } 
} 
public abstract class SomeOtherBaseClass 
{ 
    public int Id { get; set; } 
} 
public class NavigationPropertyClass : SomeOtherBaseClass 
{ 
    public Derived1 Derived1 { get; set; } 
    public virtual ICollection<Derived2> Derived2s { get; set; } 
} 

，你只需要在配置模型生成器時使用ToTable有TPT的繼承。

public class AppContext : DbContext 
{ 
    public DbSet<SomeOtherBaseClass> SomeOtherBaseClasses { get; set; } 
    public DbSet<Base> Bases { get; set; } 

    protected override void OnModelCreating(DbModelBuilder modelBuilder) 
    { 
     modelBuilder.Entity<Derived1>().ToTable("Derived1"); 
     modelBuilder.Entity<Derived2>().ToTable("Derived2"); 
     modelBuilder.Entity<NavigationPropertyClass>().ToTable("NavigationPropertyClass"); 

     modelBuilder.Entity<NavigationPropertyClass>() 
      .HasRequired(x => x.Derived1) 
      .WithRequiredDependent(x => x.NavigationProperty); 
    } 
} 

並留下一切EF convention，除非NavigationPropertyClass::Id也是FK到Derived1的組成部分。

結果

簡體上NavigationPropertyClass表生成約束：

PRIMARY KEY [Id] 
FOREIGN KEY([Id]) REFERENCES [dbo].[Derived1] ([Id]) 
FOREIGN KEY([Id]) REFERENCES [dbo].[SomeOtherBaseClasses] ([Id]) 

更多

• Mapping the Table-Per-Type (TPT) Inheritance