I have the following test code:
private class SomeItem
{
public string Title{ get{ return "something"; } }
public bool Completed { get { return false; } set { } }
}
private class SomeCollection : IEnumerable<SomeItem>, INotifyCollectionChanged
{
private IList<SomeItem> _items = new List<SomeItem>();
public void Add(SomeItem item)
{
_items.Add(item);
CollectionChanged(this, new
NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
#region IEnumerable<SomeItem> Members
public IEnumerator<SomeItem> GetEnumerator()
{
return _items.GetEnumerator();
}
#endregion
#region IEnumerable Members
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return _items.GetEnumerator();
}
#endregion
#region INotifyCollectionChanged Members
public event NotifyCollectionChangedEventHandler CollectionChanged;
#endregion
}
private SomeCollection collection = new SomeCollection();
private void Expander_Expanded(object sender, RoutedEventArgs e)
{
var expander = (Expander) sender;
var list = expander.DataContext as ITaskList;
var listBox = (ListBox)expander.Content;
//list.Tasks.CollectionChanged += CollectionChanged;
collection.Add(new SomeItem());
collection.Add(new SomeItem());
listBox.ItemsSource = collection;
}
and the XAML
<ListBox Name="taskListList" ItemsSource="{Binding}" BorderThickness="0" ItemContainerStyle="{StaticResource noSelectedStyle}" >
<ListBox.ItemTemplate>
<DataTemplate>
<Expander Expanded="Expander_Expanded">
<Expander.Header>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Name}" />
<TextBox KeyUp="TextBox_KeyUp" Width="200"/>
<Button Name="hide" Click="hide_Click">
<TextBlock Text="hide" />
</Button>
</StackPanel>
</Expander.Header>
<ListBox Name="taskList" ItemsSource="{Binding}" ItemTemplate="
{StaticResource taskItem}" />
</Expander>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
the outer listbox gets populated on load. when the expander gets expanded I then set the ItemsSource
property of the inner listbox (the reason i do this hear instead of using binding is this operation is quite slow and i only want it to take place if the use chooses to view the items). The inner listbox renders fine, but it doesn't actually subscribe to the CollectionChanged
event on the collection. I have tried this with ICollection
instead of IEnumerable
and adding INotifyPropertyChanged
as well as replacing INotifyCollectionChanged
with INotifyPropertyChanged
. The only way I can actually get this to work is to gut my SomeCollection
class and inherit from ObservableCollection<SomeItem>
. My reasoning for trying to role my own INotifyCollectionChanged
instead of using ObservableCollection
is because I am wrapping a COM collection in the real code. That collection will notify on add/change/remove and I am trying to convert these to INotify
events for WPF.
Hope this is clear enough (its late).
Best Answer
ObservableCollection<T>
also implementsINotifyPropertyChanged
. As you collection is simply anIEnumerable<T>
you don't have any properties to create events for, butObservableCollection<T>
createPropertyChanged
events for theCount
andItem[]
properties. You could try to make your collection more likeObservableCollection<T>
by deriving fromIList<T>
and implementingINotifyPropertyChanged
. I don't know if that will fix your problem, though.