How to automatically select first item in a bound silverlight listbox?

Question

Using silverlight, I have a listbox with ItemsSource bound to an ObservableCollection which is updated asynchronously. I would like to automatically select the first item in the listbox as soon as the binding is finished updating.

I can't find a good way to make this happen. I don't see any useful events to handle on the listbox and if I bind to the collection's CollectionChanged event, the binding hasn't updated yet so if I set the listbox.selectedindex at that point I get an exception that the value is out of range. Any ideas? Maybe some way to hook the binding update?

Answer 1

On the ListBox, bind the SelectedItem property to a property on your codebind or viewmodel. Then, in the async callback handler set the property to the first item in the collection and raise the PropertyChanged event for the property(unless you already raise the event in the setter of your property):

MySelectedListItem = _entitylist.FirstOrDefault();
RasisePropertyChanged("MySelectedListItem");