Question

在Entity Framework 7中，当我尝试应用迁移时，我收到了错误

在表'ChangeOrder'上引入FOREIGN KEY约束'FK_ChangeOrder_User_CreatedByID'可能会导致循环或多个级联路径。指定ON DELETE NO ACTION或ON UPDATE NO ACTION，或修改其他FOREIGN KEY约束无法创建约束。查看以前的错误。

我知道在旧版本的Entity Framework中你可以通过添加

来解决这个问题

modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();

到DbContext，但在EF7 modelBuilder中似乎没有.Conventions，谷歌只返回EF 4结果的旧版EF 4。

如何在Entity Framework 7中具体ON DELETE NO ACTION约束？

编辑： Oleg提供的答案显然是按照外键进行的，但我想在全局范围内进行，因为使用一行代码来全局声明这一点会更容易，然后必须为数百个中的每一个指定代码。关系，我最终会有。

编辑2：Oleg的代码

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

在GitHub上挖掘，并与MS的一个非常有耐心的人一起工作，目前的解决方案是将其添加到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);
}

Answer 2

施工

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

表示使用FK_ChangeOrder_User_CreatedByID创建REFERENCES [dbo].[User] ([CreatedByID]) ON DELETE CASCADE。它应该存在于迁移期间创建的protected override void BuildModel(ModelBuilder modelBuilder) YourContextModelSnapshot.cs中。我不确定我是否完全理解你的问题，但我认为你应该将这样的构造添加到XXXModelSnapshot.cs或删除不需要的构造，这已经存在于此处。

更新：我发现您在模型中遇到了问题。

中有以下属性

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; }

默认情况下，迁移尝试在所有属性上设置DeleteBehavior.Cascade。

您可以通过更改OnModelCreating来覆盖行为，DeleteBehavior.Restrict为所有密钥设置DeleteBehavior.Cascade行为，或者只设置一个密钥DeleteBehavior.SetNull或DeleteBehavior.Cascade行为。例如，下面的代码使用CreatedByID上的ON DELETE CASCADE（在外键上创建DeleteBehavior.Restrict）和其他外键上的ON DELETE使用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; } }外键）：

=SUM(IF(ISERROR($A$1:$A$3);0;$A$1:$A$3)))

在实体框架7中指定ON DELETE NO ACTION？

2 个答案: