ObjectStateEntry Class
Maintains state and key information for objects and relationships and change tracking for object properties.
Assembly: System.Data.Entity (in System.Data.Entity.dll)
Maintains the EntityState, the EntityKey values, and the original values of an object or relationship. Also manages the list of modified properties.
There is an instance of an ObjectStateEntry associated with each entity type relationship instance. An object is associated with an ObjectStateEntry only if it is in the ObjectStateManager.
When an object that has a relationship is detached, the information maintained by the ObjectStateEntry is reduced to only what is required to maintain the relationship.
An ObjectStateEntry cannot have the same key as another ObjectStateEntry in the same ObjectStateManager.
The key values of a persisted entity cannot be modified. Entities in the unchanged, modified, and deleted states are persisted entities.
The example in this topic is based on the Adventure Works Sales Model. The example gets the ObjectStateEntry for the given EntityKey from the ObjectStateManager. Then it gets the current value of SalesOrderHeader.PurchaseOrderNumber property, changes the property's value, and enumerates through the collection of modified properties.
Dim orderId As Integer = 43680 Using advWorksContext As New AdventureWorksEntities Try Dim order As SalesOrderHeader = _ advWorksContext.SalesOrderHeader.Where("it.SalesOrderID = @id", _ New ObjectParameter("id", orderId)).First() ' Get ObjectStateEntry from EntityKey. Dim stateEntry As ObjectStateEntry = _ advWorksContext.ObjectStateManager.GetObjectStateEntry(CType(order, IEntityWithKey).EntityKey) 'Get the current value of SalesOrderHeader.PurchaseOrderNumber. Dim rec1 As CurrentValueRecord = stateEntry.CurrentValues Dim oldPurchaseOrderNumber As String = _ CStr(rec1.GetValue(rec1.GetOrdinal("PurchaseOrderNumber"))) 'Change the value. order.PurchaseOrderNumber = "12345" Dim newPurchaseOrderNumber As String = _ CStr(rec1.GetValue(rec1.GetOrdinal("PurchaseOrderNumber"))) ' Get the modifed properties. Dim modifiedFields As IEnumerable(Of String) = stateEntry.GetModifiedProperties ' Get the Entity that is associated with this ObjectStateEntry. Dim s As String For Each s In modifiedFields Console.WriteLine("Modified field name: {0}" & ChrW(10) & _ " Old Value: {1}" & ChrW(10) & _ " New Value: {2}", _ s, oldPurchaseOrderNumber, newPurchaseOrderNumber) Next Dim associatedEnity As SalesOrderHeader = CType(stateEntry.Entity, SalesOrderHeader) Console.WriteLine("Associated Enity's ID: {0}", _ associatedEnity.SalesOrderID) Catch ex As EntitySqlException Console.WriteLine(ex.ToString) Catch ex As EntityCommandExecutionException Console.WriteLine(ex.ToString) End Try End Using
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.