ObjectStateManager.TryGetObjectStateEntry Method (EntityKey, ObjectStateEntry)

 
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Tries to retrieve the corresponding ObjectStateEntry for the object or relationship with the specified EntityKey.

Namespace:   System.Data.Objects
Assembly:  System.Data.Entity (in System.Data.Entity.dll)

Public Function TryGetObjectStateEntry (
	key As EntityKey,
	<OutAttribute> ByRef entry As ObjectStateEntry
) As Boolean

Parameters

key
Type: System.Data.EntityKey

The given EntityKey.

entry
Type: System.Data.Objects.ObjectStateEntry

When this method returns, contains an ObjectStateEntry for the given EntityKey This parameter is passed uninitialized.

Return Value

Type: System.Boolean

A Boolean value that is true if there is a corresponding ObjectStateEntry for the given EntityKey; otherwise, false.

Exception Condition
ArgumentNullException

A null (Nothing in Visual Basic) value is provided for key.

Use TryGetObjectStateEntry(EntityKey, ObjectStateEntry) to return an ObjectStateEntry without having to handle the InvalidOperationException raised by the GetObjectStateEntry(EntityKey) method.

The examples in this topic are based on the AdventureWorks Sales Model.

The example attempts to retrieve the corresponding ObjectStateEntry for the given EntityKey.

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

The following example uses the TryGetObjectStateEntry(EntityKey, ObjectStateEntry) method on the returned ObjectStateManager to get an object based on its entity key.

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

.NET Framework
Available since 3.5
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