在實體框架7中指定ON DELETE NO ACTION？

Question

在實體框架7中指定ON DELETE NO ACTION？

c# entity-framework-core

題

在Entity Framework 7中，當我嘗試應用遷移時，我收到錯誤

在表'ChangeOrder'上引入FOREIGN KEY約束'FK_ChangeOrder_User_CreatedByID'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。

我知道在舊版本的Entity Framework中你可以通過添加來解決這個問題

modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();

到的DbContext但EF7 modelBuilder似乎並不具有.Conventions它和谷歌只返回舊的EF 4雖然EF 6的結果。

如何在Entity Framework 7中特定ON DELETE NO ACTION約束？

編輯：奧列格提供的答案顯然是按照外鍵進行的，但我想在全局範圍內進行，因為使用一行代碼來全局聲明這一點會更容易，然後必須為每一個代碼指定代碼。我將最終擁有數百種關係。

編輯2：奧列格的代碼

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; }
}

Matthew Verstraete

熱門答案

那個工程

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

將意味著使用REFERENCES [dbo].[User] ([CreatedByID]) ON DELETE CASCADE創建FK_ChangeOrder_User_CreatedByID REFERENCES [dbo].[User] ([CreatedByID]) ON DELETE CASCADE 。它應該存在於遷移期間創建的YourContextModelSnapshot.cs protected override void BuildModel(ModelBuilder modelBuilder)中。我不確定我是否完全理解您的問題，但我認為您應該將此類構造添加到XXXModelSnapshot.cs或刪除此處已存在的不需要的構造。

更新：我看到你在模型中遇到了問題。您有以下屬性

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; }

默認情況下，遷移嘗試在所有屬性上設置DeleteBehavior.Cascade 。

您可以通過更改OnModelCreating來覆蓋行為， DeleteBehavior.Restrict為所有鍵設置DeleteBehavior.Restrict行為，或者僅在一個鍵上設置DeleteBehavior.Cascade或DeleteBehavior.SetNull行為。例如，下面的代碼使用DeleteBehavior.Cascade上CreatedByID （產生ON DELETE CASCADE上外鍵）和DeleteBehavior.Restrict上其它外鍵（無ON DELETE上外鍵）：

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; }
}

Oleg

在 Stack Overflow 上查看更多

Accepted Answer

在GitHub上挖掘，並與MS的一個非常有耐心的人一起工作，目前的解決方案是將其添加到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);
}

在實體框架7中指定ON DELETE NO ACTION？

題

Fastest Entity Framework Extensions

一般承認的答案

熱門答案

Performance

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