例外：外键约束可能会导致多个周期

Question

我是ASP .NET新手。 我正在尝试使用以下模型进行简单的CRUD。 Paper类中有三个ChartOfAccountId ，因此有三个父子关系。 这些关系ChartOfAccountIdInventory一种导致以下异常：

Introducing FOREIGN KEY constraint FK_dbo.Papers_dbo.ChartOfAccounts_ChartOfAccountIdInventory' on table 'Papers' 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.

ChartOfAccount类：

public partial class ChartOfAccount
{
    public ChartOfAccount()
    {
        this.PapersSale = new HashSet<Paper>();
        this.PapersCostOfSale = new HashSet<Paper>();
        this.PapersInventory = new HashSet<Paper>();
    }

    [StringLength(50)]
    [ScaffoldColumn(true)]
    public string Id { get; set; }

    [StringLength(50)]
    public string Name { get; set; }

    public virtual ICollection<Paper> PapersSale { get; set; }
    public virtual ICollection<Paper> PapersCostOfSale { get; set; }
    public virtual ICollection<Paper> PapersInventory { get; set; }
}

纸类：

    public class Paper
    {
        [Key]
        [ScaffoldColumn(false)]
        public int Id { get; set; }

        [DisplayName("Name")]
        [Required(ErrorMessage = "Name is required")]
        [StringLength(50)]
        public string Name { get; set; }

        [DisplayName("Chart Of Account For Sale")]
        [Required(ErrorMessage = "Chart Of Account is required")]
        [StringLength(50)]
        public string ChartOfAccountIdSale { get; set; }

        [DisplayName("Chart Of Account For Inventory")]
        [Required(ErrorMessage = "Chart Of Account is required")]
        [StringLength(50)]
        public string ChartOfAccountIdInventory { get; set; }

        [DisplayName("Chart Of Account For Cost Of Sale")]
        [Required(ErrorMessage = "Chart Of Account is required")]
        [StringLength(50)]
        public string ChartOfAccountIdCostOfSale { get; set; }

        [ForeignKey("ChartOfAccountIdSale")]
        public virtual ChartOfAccount ChartOfAccountSale { get; set; }

        [ForeignKey("ChartOfAccountIdInventory")]
        public virtual ChartOfAccount ChartOfAccountInventory { get; set; }

        [ForeignKey("ChartOfAccountIdCostOfSale")]
        public virtual ChartOfAccount ChartOfAccountCostOfSale { get; set; }
   }    

Answer 1

您应该通过fluentApi设置“ WillCascadeOnDelete = False ”，就像这样：

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
         modelBuilder.Entity<Paper>()
            .HasRequired(c => c.ChartOfAccountSale )
            //.WithMany()
            .HasForeignKey(c => c.ChartOfAccountIdSale)
            .WillCascadeOnDelete(false);

         modelBuilder.Entity<Paper>()
            .HasRequired(c => c.ChartOfAccountInventory )
            //.WithMany()
            .HasForeignKey(c => c.ChartOfAccountIdInventory )
            .WillCascadeOnDelete(false);

         modelBuilder.Entity<Paper>()
            .HasRequired(c => c.ChartOfAccountCostOfSale )
            //.WithMany()
            .HasForeignKey(c => c.ChartOfAccountIdCostOfSale )
            .WillCascadeOnDelete(false);

}

Answer 2

我对所有chartOfAccounts都使用了必需的标记，这就是它困扰异常的原因。