當不需要屬性時，引入外鍵約束可能會導致循環或多個級聯路徑

Question

我收到此錯誤：

在表'STCIProductInteractiveInfoes'上引入FOREIGN KEY約束'FK_dbo.STCIProductInteractiveInfoes_dbo.User_ModifyUserID'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。

因此，我在線上（在stackoverflow上）進行了查詢，發現這可能是因為需要外鍵。 我注釋掉了必需的屬性，但仍然出現此錯誤。

這是我的課：

namespace PTEManager.Domain
{
    public class PTEInteractiveCourse
    {
        [Key]
        public Guid PTEInteractiveCourseId { get; set; }

        [ScaffoldColumn(false)]
        [Required]
        public DateTime ModifyDate { get; set; }

        [ScaffoldColumn(false)]
        [ForeignKey("ModifyUser")]
        //[Required]
        public int ModifyUserId { get; set; }

        public virtual OpsUser ModifyUser { get; set; }

        [Display(Name = "Package")]
        [Required]
        public int PackageId { get; set; }

        [ScaffoldColumn(false)]
        [Display(Name = "")]
        [Required]
        public int Status { get; set; }

        [Display(Name = "STCI Course")]
        [ForeignKey("STCICourseID")]
        [Required]
        public Guid STCIProductInteractiveInfoID { get; set; }

        public virtual STCIProductInteractiveInfo STCICourseID { get; set; }
    }
}

這是它崩潰的代碼：

[HttpGet]
public ActionResult Index()
{
     var model = db.PTEInteractiveCourses
           .Where(p => p.Status == 1)
           .ToList();

     return View(model);
}

當用戶刪除交互式課程時，不應從用戶表中刪除該用戶。 只是互動課程應該被刪除。 在LINQ查詢上會發生哪個錯誤以列出數據，所以我什至不知道要刪除它有什么關系，無論如何我們都不會添加刪除功能。 好吧，將會有一個刪除，但是它所要做的就是向用戶隱藏交互過程，但是它將保存數據以防止數據丟失。

我找到了以下代碼：

protected override void OnModelCreating( DbModelBuilder modelBuilder )
{
    modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
}

從理論上講這應該可行，因為我不需要此項目的任何級聯刪除，但是我將把這些代碼放在哪里？ 它在我的datacontext類中說，但是當我這樣做時，void關鍵字上出現構建錯誤。 這是我的datacontext類：

namespace PTEManager.Domain.Data
{
    public class DataContext : DbContext, IDataContext
    {
        public DataContext()
            : base("HelpDesk")
        {
        }

        //public DataContext(DbConnection existingConnection, bool contextOwnsConnection)
        //    : base(existingConnection, contextOwnsConnection)
        //{
        //}
        /// <summary>
        /// any entity to be persisted must be declared here.
        /// </summary>
        /// 
        public DbSet<OpsUser> OpsUsers { get; set; }

        public DbSet<PTEInteractiveCourse> PTEInteractiveCourses { get; set; }

        public DbSet<PTETrackingClass> PTETrackingClasses { get; set; }

        public DbSet<STCIProductInteractiveInfo> STCIProductInteractiveInfos { get; set; }


    }

}

OpsUser類別：

namespace PTEManager.Domain
{
    [Table("User")]
    public class OpsUser
    {
        [Key]
        public int u_user_id { get; set; }

        public Guid DepartmentID { get; set; }

        [MaxLength(50)]
        [Required]
        public string email_addr { get; set; }

        [MaxLength(30)]
        [Required]
        public string first_nme { get; set; }

        [MaxLength(30)]
        [Required]
        public string last_nme { get; set; }

        [Required]
        public Guid msrepl_tran_version { get; set; }

        [MaxLength(1)]
        [Required]
        public string status { get; set; }

        [MaxLength(15)]
        [Required]
        public string user_nme { get; set; }

        [Required]
        public int u_branch_id { get; set; }

    }
}

PTETrackingClass：

namespace PTEManager.Domain
{
    public class PTETrackingClass
    {
        [Key]
        public Guid PTETrackingClassId { get; set; }

        [ScaffoldColumn(false)]
        [Required]
        public DateTime ModifyDate { get; set; }


        [ScaffoldColumn(false)]
        [ForeignKey("ModifyUser")]
        [Required]
        public int ModifyUserId { get; set; }

        public virtual OpsUser ModifyUser { get; set; }

        [Display(Name = "Extensions Allowed")]
        [Required]
        public int NumberOfExtensions { get; set; }

        [ScaffoldColumn(false)]
        [Required]
        public int Status { get; set; }

        [Display(Name="Tracking Class Code")]
        [Required]
        public Guid TrackingClassCode { get; set; }

    }
}

STCIProductInteractiveInfo：

namespace PTEManager.Domain
{
    public class STCIProductInteractiveInfo
    {
        [Key]
        public Guid STCIProductInteractiveInfoID { get; set; }

        public Guid MarketingTextID { get; set; }

        [Required]
        public DateTime ModifyDate { get; set; }

        [ForeignKey("ModifyUser")]
        //[Required]
        public int ModifyUserID { get; set; }

        public virtual OpsUser ModifyUser { get; set; }

        [MaxLength(50)]
        [Required]
        public string STCICourseID { get; set; }

        [MaxLength(100)]
        [Required]
        public string STCICourseName { get; set; }

        public byte STCIProductEmailHTML { get; set; }

        [MaxLength(255)]
        public string STCIProductEmailHTMLDateType { get; set; }

        public int STCIProductEmailHTMLFileLength { get; set; }

        public byte STCIProductEmailText { get; set; }

        [MaxLength(255)]
        public string STCIProductEmailTextDataType { get; set; }
        public string STCIProductEmailTextFileLength { get; set; }

        [MaxLength(50)]
        [Required]
        public string STCITrackingClassCode { get; set; }

        [MaxLength(100)]
        [Required]
        public string STCITrackingClassName { get; set; }

        [Required]
        public int u_product_id { get; set; }

    }
}

Answer 1

您的表上有一個循環關系，以解決必須選擇的問題：

1）如果用戶在STCIProductInteractiveInfo或PTEInteractiveCourse是可選的， STCIProductInteractiveInfo只需更改

public class STCIProductInteractiveInfo // or PTEInteractiveCourse
{
    [Required]
    public int ModifyUserID { get; set; }
}

至

public class STCIProductInteractiveInfo // or PTEInteractiveCourse
{
    // [Required] remove required attribute too
    public int? ModifyUserID { get; set; }
}

2）但是如果您想保留User Required只需在DbContext上添加它即可

public class DataContext : DbContext, IDataContext
{
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<STCIProductInteractiveInfo>()
            .HasRequired(e => e.ModifyUser)
            .WithMany()
            .WillCascadeOnDelete(false);
    }
}