Entity Framework 当 IDENTITY_INSERT 设置为 OFF 时，多对多插入抛出错误无法在 table 中插入标识列的显式值

Question

我创建了一个从数据库创建的代码优先模型，所以我有我的实体和上下文的所有设置。这是有问题的 table 的图表。 Many to Many relation diagram 如果有意义的话，关系是为了知道哪个付款涵盖了哪些订单。我试图通过将 SalesOrder 实例添加到 EF 中的 payment.SalesOrders 来向 PaymentSalesOrder 添加记录。调用 SaveChanges() 时出现此错误：

ErrorCode

Cannot insert explicit value for identity column in table 'PaymentSalesOrder' >when IDENTITY_INSERT is set to OFF.

这是代码，基本上我查询当前客户的数据库并包括他的付款和订单。我将付款分配给销售订单并更改付款和销售订单以反映它们的可用性。最后我将 salesOrder 添加到付款中并调用 SaveChanges()。

我有一个客户在数据库中有一份订单和一笔付款，因此此代码中的所有实体都填充了正确的数据。

Code

Using db As New eRestaurantEF.Context
        If _customer Is Nothing Then
            Exit Sub
        End If
        Dim tmpCustomer As eRestaurantEF.Customer
        tmpCustomer = (From tmp In db.Customers.Include("Payments").Include("SalesOrders")
                       Where tmp.customerID = _customer.customerID
                       Select tmp).FirstOrDefault

        For Each paymentRow As eRestaurantEF.Payment In tmpCustomer.Payments
            If paymentRow.PaymentRemainder > 0 Then

                For Each orderRow As eRestaurantEF.SalesOrder In tmpCustomer.SalesOrders
                    db.SalesOrders.Attach(orderRow)
                    db.Entry(orderRow).State = Entity.EntityState.Unchanged
                    If paymentRow.PaymentRemainder > 0 Then

                        If Not orderRow.FullyPaid Then

                            If paymentRow.PaymentRemainder >= orderRow.Remainder Then
                                Dim remainder As Decimal
                                remainder = paymentRow.PaymentRemainder
                                remainder -= orderRow.Remainder

                                paymentRow.PaymentRemainder = remainder
                                orderRow.Remainder = 0
                                orderRow.IsPaid = True
                                orderRow.IsCredit = True
                                orderRow.FullyPaid = True
                                paymentRow.SalesOrders.Add(orderRow)

                            ElseIf paymentRow.PaymentRemainder <= orderRow.Total Then
                                Dim remainder As Decimal
                                remainder = paymentRow.PaymentRemainder
                                remainder -= orderRow.Remainder

                                If remainder = 0 Then
                                    paymentRow.PaymentRemainder = 0
                                    orderRow.Remainder = 0
                                    orderRow.IsPaid = True
                                    orderRow.IsCredit = True
                                    orderRow.FullyPaid = True
                                    paymentRow.SalesOrders.Add(orderRow)
                                    Exit For

                                ElseIf remainder < 0 Then
                                    paymentRow.PaymentRemainder = 0
                                    orderRow.Remainder = Math.Abs(remainder)
                                    orderRow.IsPaid = False
                                    orderRow.IsCredit = True
                                    orderRow.FullyPaid = False
                                    orderRow.Payments.Add(paymentRow)
                                    Exit For

                                End If
                            End If
                        End If
                    End If
                Next 'OrdersList
            End If
        Next 'PaymentsList

        db.SaveChanges()
    End Using

这是关系 table:

的 Fluent Api

modelBuilder.Entity(Of Payment)() _
    .HasMany(Function(e) e.SalesOrders) _
    .WithMany(Function(e) e.Payments) _
    .Map(Function(m) m.ToTable("PaymentSalesOrder").MapLeftKey("Payment_ID").MapRightKey("SalesOrder_No"))

PaymentSalesOrder table 中的两个 FK 都是在数据库中创建的复合键的一部分，以确保没有重复的行。我什至尝试删除密钥并将其更改为唯一索引，但问题仍然存在。这是来自 Sql 的 table 脚本：

CREATE TABLE [dbo].[PaymentSalesOrder](
    [Payment_ID] [int] IDENTITY(1,1) NOT NULL, <---- Here is the culprit remove the identity from this column
    [SalesOrder_No] [int] NOT NULL,
    CONSTRAINT [PK_PaymentSalesOrder] PRIMARY KEY CLUSTERED 
(
    [Payment_ID] ASC,
    [SalesOrder_No] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[PaymentSalesOrder]  WITH CHECK ADD  CONSTRAINT [FK_PaymentSalesOrder_Payment] FOREIGN KEY([Payment_ID])
REFERENCES [dbo].[Payment] ([PaymentID])
GO
ALTER TABLE [dbo].[PaymentSalesOrder] CHECK CONSTRAINT [FK_PaymentSalesOrder_Payment]
GO
ALTER TABLE [dbo].[PaymentSalesOrder]  WITH CHECK ADD  CONSTRAINT [FK_PaymentSalesOrder_SalesOrder] FOREIGN KEY([SalesOrder_No])
REFERENCES [dbo].[SalesOrder] ([SalesOrderNo])
GO

ALTER TABLE [dbo].[PaymentSalesOrder] CHECK CONSTRAINT [FK_PaymentSalesOrder_SalesOrder]
GO

很抱歉拖了这么久 post 但这真的很让人抓狂，我看不出问题出在哪里。我正在考虑把多对多的关系全部去掉，但不知道原因就放弃对我来说并不容易，如果我再次遇到它怎么办。

Answer 1

错误清楚地表明您正试图在 IDENTITY 列中插入一个值，但您不能将值插入 IDENTITY 列，在您的情况下是 Payment_ID PaymentSalesOrder table。 IDENTITY 当您通过增加提供的 INCREMENT 值插入新行时，列自动生成其值，在您的情况下是 1。我的意思是，每当您插入新行时，Payment_ID 的值将从 1 开始自动插入，并且会为每个新行递增 1。

您可以获得有关 IDENTITY here 的更多信息。

希望你现在清楚了

Entity Framework 当 IDENTITY_INSERT 设置为 OFF 时，多对多插入抛出错误无法在 table 中插入标识列的显式值

Entity Framework Many-to-Many Insert throws error Cannot insert explicit value for identity column in table when IDENTITY_INSERT is set to OFF

vb.net

sql-server

many-to-many

entity-framework

ErrorCode

Code