在Entity Framework 7中指定ON DELETE NO ACTION？ [英] Specifying ON DELETE NO ACTION in Entity Framework 7?

问题描述

在Entity Framework 7中，当我尝试应用迁移时，出现错误

In Entity Framework 7 when I am trying to apply a migration I get the error

在表上引入FOREIGN KEY约束'FK_ChangeOrder_User_CreatedByID' ChangeOrder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。请参阅先前的错误。

Introducing FOREIGN KEY constraint 'FK_ChangeOrder_User_CreatedByID' on table 'ChangeOrder' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Could not create constraint. See previous errors.

我知道在较旧版本的Entity Framework中，您可以通过添加

I know in older versions of Entity Framework you would deal with this by adding

modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();

到DbContext，但是在EF7中， modelBuilder 可以似乎没有。Conventions，Google只会通过EF 6结果返回较旧的EF 4。

to the DbContext but in EF7 modelBuilder does not seem to have a .Conventions to it and google is only returning older EF 4 though EF 6 results.

如何在Entity Framework 7中指定 ON DELETE NO ACTION 约束？

How do I specific the ON DELETE NO ACTION constraint in Entity Framework 7?

编辑：
Oleg提供的答案显然将针对每个外键进行，但我想全局进行，因为使用一行代码在全局进行声明要容易得多，然后必须为数百个关系中的每一个指定代码

The answer provided by Oleg will apparently do it per Foreign Key but I would like to do it globally as it will much easier to use one line of code to declare this globally then have to specify code it out for every single one of the hundreds of relationships I will end up having.

编辑2：Oleg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; }
}

推荐答案

在GitHub上进行挖掘后，并与来自MS的一个非常耐心的人一起工作，当前的解决方案是将其添加到DbContext

After digging around on GitHub, and working with a very patient guy from MS there, the current solution is to add this to the 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);
}

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