Filtering an ObservableCollection?

Question

When I bind a ListBox directly to an ObservableCollection I get the real-time updates displayed in my ListBox, but as soon as I add other LINQ methods in the mix my ListBox

Answer 1

You should use the ICollectionView.Filter property:

ICollectionView view = CollectionViewSource.GetDefaultView(Words);
view.Filter = WordFilter;

...


bool WordFilter(object o)
{
    string w = (string)o;
    return w.Contains(":")
}

Answer 2

Why it does not work:

listBox1.ItemsSource = Words.Where(w => w.Contains(":"));

Your are not binding the ObservableCollection but the IEnumerable generated by Linq. This new "list" does not notify the ListBox about changes in the list.

Answer 3

Try using the CollectionViewSource like this:

WordsView = new CollectionViewSource();
WordsView.Filter += Words_Filter;
WordsView.Source = Words;

// ...
void Words_Filter(object sender, FilterEventArgs e)
{
    if (e.Item != null)
        e.Accepted = ((string)e.Item).Contains(":");
}