本文整理匯總了VB.NET中System.Data.Objects.ObjectStateManager類的典型用法代碼示例。如果您正苦於以下問題：VB.NET ObjectStateManager類的具體用法？VB.NET ObjectStateManager怎麽用？VB.NET ObjectStateManager使用的例子？那麽, 這裏精選的類代碼示例或許可以為您提供幫助。
在下文中一共展示了ObjectStateManager類的2個代碼示例，這些例子默認根據受歡迎程度排序。您可以為喜歡或者感覺有用的代碼點讚，您的評價將有助於係統推薦出更棒的VB.NET代碼示例。
示例1: AdventureWorksEntities
Dim orderId As Integer = 43680
Using context As New AdventureWorksEntities()
Dim objectStateManager As ObjectStateManager = context.ObjectStateManager
Dim stateEntry As ObjectStateEntry = Nothing
Dim order = (From o In context.SalesOrderHeaders
Where o.SalesOrderID = orderId
Select o).First()
' Attempts to retrieve ObjectStateEntry for the given EntityKey.
Dim isPresent As Boolean = objectStateManager.TryGetObjectStateEntry(DirectCast(order, IEntityWithKey).EntityKey, stateEntry)
If isPresent Then
Console.WriteLine("The entity was found")
End If
End Using示例2: ApplyItemUpdates
Private Shared Sub ApplyItemUpdates(ByVal originalItem As SalesOrderDetail, ByVal updatedItem As SalesOrderDetail)
Using context As New AdventureWorksEntities()
context.SalesOrderDetails.Attach(updatedItem)
' Check if the ID is 0, if it is the item is new.
' In this case we need to chage the state to Added.
If updatedItem.SalesOrderDetailID = 0 Then
' Because the ID is generated by the database we do not need to
' set updatedItem.SalesOrderDetailID.
context.ObjectStateManager.ChangeObjectState(updatedItem, System.Data.EntityState.Added)
Else
' If the SalesOrderDetailID is not 0, then the item is not new
' and needs to be updated. Because we already added the
' updated object to the context we need to apply the original values.
' If we attached originalItem to the context
' we would need to apply the current values:
' context.ApplyCurrentValues("SalesOrderDetails", updatedItem);
' Applying current or original values, changes the state
' of the attached object to Modified.
context.ApplyOriginalValues("SalesOrderDetails", originalItem)
End If
context.SaveChanges()
End Using
End Sub