ObjectContext.ObjectStateManager Properti

Definisi

Ruang nama:

System.Data.Objects

Rakitan:

System.Data.Entity.dll

Mendapatkan manajer status objek yang digunakan oleh konteks objek untuk melacak perubahan objek.

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

Nilai Properti

ObjectStateManager

yang ObjectStateManager digunakan oleh ini ObjectContext.

Contoh

Contoh ini mendapatkan ObjectStateManager dari ObjectContext dan menggunakan manajer status untuk mengakses objek dalam konteks.

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");
    }
}

Contoh ini menggunakan TryGetObjectStateEntry metode pada yang dikembalikan ObjectStateManager untuk mendapatkan objek berdasarkan kunci entitasnya.

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();
    }
}

Lihat juga

• Bekerja dengan Objek (Kerangka Kerja Entitas)