ObjectContext.Refresh Method (RefreshMode, Object)
Updates an object in the object context with data from the data source.
Assembly: System.Data.Entity (in System.Data.Entity.dll)
'Declaration Public Sub Refresh ( _ refreshMode As RefreshMode, _ entity As Object _ )
Refresh has the dual purpose of allowing an object to be refreshed with data from the data source and being the mechanism by which conflicts can be resolved. For more information, see Saving Changes and Managing Concurrency (Entity Framework).
The order in which objects are refreshed is nondeterministic.
After the Refresh method is called, the object’s original values will always be updated with the data source value, but the current values might or might not be updated with the data source value. This depends on the RefreshMode. The StoreWins mode means that the object should be updated to match the data source values. The ClientWins value means that only the changes in the object context will be persisted, even if there have been other changes in the data source.
This example is based on the Adventure Works Sales Model. The example tries to save changes, and this may cause a concurrency conflict. Then it shows how to resolve the concurrency conflict by refreshing the object context before re-saving changes.
Using context As New AdventureWorksEntities() Try ' Perform an operation with a high-level of concurrency. ' Change the status of all orders without an approval code. Dim orders As ObjectQuery(Of SalesOrderHeader) = context.SalesOrderHeaders.Where("it.CreditCardApprovalCode IS NULL").Top("100") For Each order As SalesOrderHeader In orders ' Reset the order status to 4 = Rejected. order.Status = 4 Next Try ' Try to save changes, which may cause a conflict. Dim num As Integer = context.SaveChanges() Console.WriteLine("No conflicts. " & num.ToString() & " updates saved.") Catch generatedExceptionName As OptimisticConcurrencyException ' Resolve the concurrency conflict by refreshing the ' object context before re-saving changes. context.Refresh(RefreshMode.ClientWins, orders) ' Save changes. context.SaveChanges() Console.WriteLine("OptimisticConcurrencyException handled and changes saved") End Try For Each order As SalesOrderHeader In orders Console.WriteLine(("Order ID: " & order.SalesOrderID.ToString() & " Order status: ") + order.Status.ToString()) Next Catch ex As UpdateException Console.WriteLine(ex.ToString()) End Try End Using
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.