在Entity Framework 7中指定ON DELETE NO ACTION？

Question

在實體框架7時，我嘗試應用遷移我的錯誤

引進國外KEY約束「FK_ChangeOrder_User_CreatedByID」表「ChangeOrder」可能會導致循環或多個級聯路徑。指定ON DELETE NO ACTION或ON UPDATE NO ACTION，或修改其他FOREIGN KEY約束。
無法創建約束。查看以前的錯誤。

我知道在老版本的實體框架，你會處理這種通過增加

modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>(); 

到的DbContext但EF7 modelBuilder似乎並不有.Conventions它和谷歌只返回舊的EF 4通過EF 6結果。

如何特定實體框架7中的ON DELETE NO ACTION約束？

編輯： 由Oleg提供的答案顯然會做到每個外鍵，但我想全局做它，因爲它會更容易使用一行代碼來全局聲明這一點，然後必須指定代碼出來我將最終擁有的數百種關係中的每一種。

編輯2：代碼奧列格

public class ChangeOrder 
{ 
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
    public int ID { get; set; } 

    public Int16? ApprovedByID { get; set; } 
    public Byte ApprovalStatusID { get; set; } 
    public Int16 AssignedToID { get; set; } 
    public Int16 CreatedByID { get; set; } 
    public Byte CurrentStatusID { get; set; } 
    public DateTime? DateApproved { get; set; } 
    public DateTime? EndDate { get; set; } 
    public Byte ImpactID { get; set; } 
    public Byte PriorityID { get; set; } 
    public DateTime? StartDate { get; set; } 
    public Byte TypeID { get; set; } 

    [Required] 
    public string Name { get; set; } 

    [Required] 
    public string ReasonForChange { get; set; } 

    [ForeignKey("ApprovedByID")] 
    public User ApprovedBy { get; set; } 

    [ForeignKey("ApprovalStatusID")] 
    public ChangeApprovalStatus ApprovalStatus { get; set; } 

    [ForeignKey("AssignedToID")] 
    public User AssignedTo { get; set; } 

    [ForeignKey("CreatedByID")] 
    public User CreatedBy { get; set; } 

    [ForeignKey("ImpactID")] 
    public ChangeImpact Impact { get; set; } 

    [ForeignKey("PriorityID")] 
    public ChangePriority Priority { get; set; } 

    [ForeignKey("TypeID")] 
    public ChangeType ChangeType { get; set; } 

    [ForeignKey("CurrentStatusID")] 
    public ChangeStatus CurrentStatus { get; set; } 
} 

public class JobSightDBContext : DbContext 
{ 
    protected override void OnModelCreating(ModelBuilder modelbuilder) 
    { 
     base.OnModelCreating(modelbuilder); 
    } 

    DbSet<ChangeApprovalStatus> ChangeApprovalStatus { get; set; } 
    DbSet<ChangeImpact> ChangeImapct { get; set; } 
    DbSet<ChangeOrder> ChangeOrders { get; set; } 
    DbSet<ChangePriority> ChangePriorities { get; set; } 
    DbSet<ChangeStatus> ChangeStatus { get; set; } 
    DbSet<ChangeType> ChangeTypes { get; set; } 
    DbSet<User> Users { get; set; } 
} 

Answer 1

上GitHut周圍挖掘，並與工作後從MS GitHub上非常專利傢伙目前的解決辦法是把它添加到的DbContext

protected override void OnModelCreating(ModelBuilder modelbuilder) 
{ 
    foreach (var relationship in modelbuilder.Model.GetEntityTypes().SelectMany(e => e.GetForeignKeys())) 
    { 
     relationship.DeleteBehavior = DeleteBehavior.Restrict; 
    } 

    base.OnModelCreating(modelbuilder); 
} 

Answer 2

建設

modelBuilder.Entity("myNamespace.Models.ChangeOrder", b => 
    { 
     b.HasOne("myNamespace.Models.User") 
      .WithMany() 
      .HasForeignKey("CreatedByID") 
      .OnDelete(DeleteBehavior.Cascade); 
    }); 

將意味着創造FK_ChangeOrder_User_CreatedByID與REFERENCES [dbo].[User] ([CreatedByID]) ON DELETE CASCADE。它應該存在於遷移期間創建的protected override void BuildModel(ModelBuilder modelBuilder)的YourContextModelSnapshot.cs。我不確定我是否完全理解了您的問題，但我認爲您應該將此構造添加到XXXModelSnapshot.cs或刪除此處已存在的不需要的構造。

更新：我看到你在模型中有問題。你有

public Int16? ApprovedByID { get; set; } 
public Int16 AssignedToID { get; set; } 
public Int16 CreatedByID { get; set; } 

// navigation properties 

[ForeignKey("ApprovedByID")] 
public User ApprovedBy { get; set; } 

[ForeignKey("AssignedToID")] 
public User AssignedTo { get; set; } 

[ForeignKey("CreatedByID")] 
public User CreatedBy { get; set; } 

下列屬性默認情況下遷移嘗試設置DeleteBehavior.Cascade上的所有屬性。

你可以通過改變OnModelCreating，其中規定無論是DeleteBehavior.Restrict行爲所有鍵或在一組唯一的關鍵的DeleteBehavior.Cascade或DeleteBehavior.SetNull行爲覆蓋的行爲。例如，下面的代碼使用上CreatedByIDDeleteBehavior.Cascade（產生ON DELETE CASCADE的外鍵）上的其它外鍵（上外鍵沒有ON DELETE）和DeleteBehavior.Restrict：

public class JobSightDBContext : DbContext 
{ 
    protected override void OnModelCreating(ModelBuilder modelbuilder) 
    { 
     base.OnModelCreating(modelbuilder); 

     modelbuilder.Entity(typeof (ChangeOrder)) 
      .HasOne(typeof (User), "ApprovedBy") 
      .WithMany() 
      .HasForeignKey("ApprovedByID") 
      .OnDelete(DeleteBehavior.Restrict); // no ON DELETE 
     modelbuilder.Entity(typeof (ChangeOrder)) 
      .HasOne(typeof (User), "AssignedTo") 
      .WithMany() 
      .HasForeignKey("AssignedToID") 
      .OnDelete(DeleteBehavior.Restrict); // no ON DELETE 
     modelbuilder.Entity(typeof (ChangeOrder)) 
      .HasOne(typeof (User), "CreatedBy") 
      .WithMany() 
      .HasForeignKey("CreatedByID") 
      .OnDelete(DeleteBehavior.Cascade); // set ON DELETE CASCADE 
    } 

    DbSet<ChangeApprovalStatus> ChangeApprovalStatus { get; set; } 
    DbSet<ChangeImpact> ChangeImapct { get; set; } 
    DbSet<ChangeOrder> ChangeOrders { get; set; } 
    DbSet<ChangePriority> ChangePriorities { get; set; } 
    DbSet<ChangeStatus> ChangeStatus { get; set; } 
    DbSet<ChangeType> ChangeTypes { get; set; } 
    DbSet<User> Users { get; set; } 
}