ObjectContext.ObjectStateManager Property
Definition
Important
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Gets the object state manager used by the object context to track object changes.
public:
property System::Data::Objects::ObjectStateManager ^ ObjectStateManager { System::Data::Objects::ObjectStateManager ^ get(); };
public System.Data.Objects.ObjectStateManager ObjectStateManager { get; }
member this.ObjectStateManager : System.Data.Objects.ObjectStateManager
Public ReadOnly Property ObjectStateManager As ObjectStateManager
Property Value
The ObjectStateManager used by this ObjectContext.
Examples
These examples are based on the Microsoft SQL Server Product Samples: Database. This example gets the ObjectStateManager from the ObjectContext and uses the state manager to access an object in the context.
int orderId = 43680;
using (AdventureWorksEntities context =
new AdventureWorksEntities())
{
ObjectStateManager objectStateManager = context.ObjectStateManager;
ObjectStateEntry stateEntry = null;
var order = (from o in context.SalesOrderHeaders
where o.SalesOrderID == orderId
select o).First();
// Attempts to retrieve ObjectStateEntry for the given EntityKey.
bool isPresent = objectStateManager.TryGetObjectStateEntry(((IEntityWithKey)order).EntityKey, out stateEntry);
if (isPresent)
{
Console.WriteLine("The entity was found");
}
}
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
This example uses the TryGetObjectStateEntry method on the returned ObjectStateManager to get an object based on its entity key.
private static void ApplyItemUpdates(SalesOrderDetail originalItem,
SalesOrderDetail updatedItem)
{
using (AdventureWorksEntities context =
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)
{
// 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);
}
context.SaveChanges();
}
}
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