WPF ObjectContext Attach Detach - Not Working

Question

Hello,

I am implementing an ObservableCollection to manage my EF entities. When i want to edit some entity, i create a clone of the entity and i open it up inside a popup window. When the user finishes to edit the cloned entity, i proceed to detach the original entity and then attach the new (cloned and edited) entity.

No exception occurs, but no update occurs to the db.

Here is the method that performs the update. It is an override of the ObservableCollection SetItem method :

protected override void SetItem(int index, T item)
    {
        T oldItem = Items.ElementAt(index);
        base.SetItem(index, item);

        try
        {
            ContextManager.CurrentObjectContext.Detach(oldItem);
            ContextManager.CurrentObjectContext.Attach((IEntityWithKey)item);
            ContextManager.CurrentObjectContext.SaveChanges();

        }
        catch (Exception err)
        {
            base.SetItem(index, oldItem);
            MessageBox.Show(err.Message);
        }
    }

Will greatly appriciate any help...

Thanks in advance, Oran

Answer 1

Your cloned entity does not track changes so when you attach it, it is still in unchanged state. Try to add this line after attaching:

ContextManager.CurrentObjectContext.ObjectStateManager.ChangeObjectState(item, EntityState.Modified);

You can also try to use this one instead:

ContextManager.CurrentObjectContext.DetectChanges(item);