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ObjectContext.SaveChanges Method

Persists all updates to the data source and resets change tracking in the object context.

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

public int SaveChanges()

Return Value

Type: System.Int32
The number of objects in an Added, Modified, or Deleted state when SaveChanges was called.

ExceptionCondition
OptimisticConcurrencyException

An optimistic concurrency violation has occurred in the data source.

To ensure that objects on the client have been updated by data source-side logic, you can call the Refresh method with the StoreWins value after you call SaveChanges. For more information, see Saving Changes and Managing Concurrency (Entity Framework).

SaveChanges operates within a transaction. SaveChanges will roll back that transaction and throw an exception if any of the dirty ObjectStateEntry objects cannot be persisted.

If an optimistic concurrency violation has occurred, an OptimisticConcurrencyException is thrown. You can resolve an optimistic concurrency violation by catching it, calling the Refresh method with the StoreWins or ClientWins value, and then calling SaveChanges again. For more information, see How to: Manage Data Concurrency in the Object Context (Entity Framework).

This example is based on the Adventure Works Sales Model. This example tries to save changes, which may cause a concurrency conflict. Then, it demonstrates how to resolve the concurrency conflict by refreshing the object context before re-saving changes.

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    try
    {
        // Perform an operation with a high-level of concurrency. 
        // Change the status of all orders without an approval code.
        ObjectQuery<SalesOrderHeader> orders =
            context.SalesOrderHeaders.Where(
            "it.CreditCardApprovalCode IS NULL").Top("100");

        foreach (SalesOrderHeader order in orders)
        {
            // Reset the order status to 4 = Rejected.
            order.Status = 4;
        }
        try
        {
            // Try to save changes, which may cause a conflict. 
            int num = context.SaveChanges();
            Console.WriteLine("No conflicts. " +
                num.ToString() + " updates saved.");
        }
        catch (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");
        }

        foreach (SalesOrderHeader order in orders)
        {
            Console.WriteLine("Order ID: " + order.SalesOrderID.ToString()
                + " Order status: " + order.Status.ToString());
        }
    }
    catch (UpdateException ex)
    {
        Console.WriteLine(ex.ToString());
    }
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5 SP1

.NET Framework Client Profile

Supported in: 4

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.

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