EntityFramework尝试创建指向同一个表的多个链接，FK Constraint错误

Posted 2021-03-27

我有一个名为DeliveryRequest的表和另一个名为Operator的表，表DeliveryRequest如下：

public class DeliveryRequest
{
    public int ID { get; set; }
    public DateTime Date { get; set; }
    public string UserID { get; set; }
    public string Waybill { get; set; }
    public string Reference { get; set; }
    public int SupplierID { get; set; }
    public Supplier Supplier { get; set; }
    //[ForeignKey("Operator")]
    public int SenderID { get; set; }
    public Operator Sender { get; set; }
    //[ForeignKey("Operator")]
    public int ReceiverID { get; set; }
    public Operator Receiver { get; set; }
    public string Origin { get; set; }
    public string Destination { get; set; }
    public int ServiceID { get; set; }
    public Service Service { get; set; }
}

而表运算符如下：

public class Operator
{
    public int ID { get; set; }
    public string Company { get; set; }
    public int ContactID { get; set; }
    public Contact Contact { get; set; }
    public int AddressID { get; set; }
    public Address Address { get; set; }
}

所以问题是，当我尝试更新我的数据库时，我得到一个FK约束错误，如下所示：

在表'DeliveryRequests'上引入FOREIGN KEY约束'FK_dbo.DeliveryRequests_dbo.Operators_SenderID'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。无法创建约束或索引。查看以前的错误。

而之前的错误是一样的。如下：

System.Data.SqlClient.SqlException（0x80131904）：在表'DeliveryRequests'上引入FOREIGN KEY约束'FK_dbo.DeliveryRequests_dbo.Operators_SenderID'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。

专注于发件人和接收者部分，我不是专家，但错误必须在那里大声笑

//[ForeignKey("Operator")]
public int SenderID { get; set; }
public Operator Sender { get; set; }
//[ForeignKey("Operator")]
public int ReceiverID { get; set; }
public Operator Receiver { get; set; }

答案

看起来你正在使用Code First方法。因此，请尝试为DeliveryRequests关闭CascadeDelete：

modelBuilder.Entity<DeliveryRequests>()
    .HasRequired(c => c.Operator )
    .WithMany()
    .WillCascadeOnDelete(false);

例如：

public class YourDBContext: DbContext 
{
    public YourDBContext(): base() 
    {
    }


    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<DeliveryRequests>()
            .HasRequired(c => c.Operator )
            .WithMany()
            .WillCascadeOnDelete(false);    
    }
}