我有一系列儿童用品,我不想删除,然后添加新的.
我不关心性能,因为它是一种非常频繁的操作.
我不关心性能,因为它是一种非常频繁的操作.
我该怎么办？我尝试过Order.items.clear()和Order.Items.Remove(x),但两者都给我例外
简化代码：
Dim db As New MainDataDataContext
dim o as Order = (From Order In db.Orders Where Order.OrderID = OrderID).FirstOrDefault
''//this will return "An attempt was made to remove a
''//relationship between a Order and a OrderItem.
''//However,one of the relationship's foreign keys
''//(Order.OrderID) cannot be set to null." exception
o.Items.Clear()
''//and this will return "EntitySet was modified during enumeration." exception
For Each oItem As OrderItem In o.Items
o.items.Remove(oItem)
Next
For Each item As ListViewItem In listViewOrderItems.Items
If item.ItemType = ListViewItemType.DataItem Then
Dim oItem As New OrderItem
oItem.OrderID = OrderID
oItem.Product = CType(item.FindControl("txtProduct"),TextBox).Text
oItem.Quantity = CType(item.FindControl("txtQuantity"),TextBox).Text
Order.items.Add(oItem)
End If
Next
db.SubmitChanges()
解决方法
只要您删除所有项目,您也可以使用
db.OrderItems.DeleteAllOnSubmit(o.Items);
