#986 – Filtering a ListBox Using a CollectionViewSource

When populating a ListBox from a CollectionViewSource, you can also filter the data.  Below is an example of a ListBox that is bound to a CollectionViewSource.

    <Window.Resources>
        <CollectionViewSource x:Key="cvsActors" Source="{Binding ActorList}" >
            <CollectionViewSource.SortDescriptions>
                <scm:SortDescription PropertyName="LastName" />
            </CollectionViewSource.SortDescriptions>
        </CollectionViewSource>
    </Window.Resources>

    <StackPanel>
        <ListBox Name="lbActors" Margin="15" Width="200" Height="200"
                 ItemsSource="{Binding Source={StaticResource cvsActors}}"/>
        <CheckBox Content="Only Joans" IsChecked="{Binding OnlyJoans}"
                  Margin="15"/>
    </StackPanel>

In code, we add a handler for the Filter event of the CollectionViewSource.  The handler is called for each item in the list.

            // Requires: using System.Windows.Data
            ((CollectionViewSource)this.Resources["cvsActors"]).Filter += ActorList_Filter;

In the handler, we set the Accepted property of the argument if the item should be included in the list.

        void ActorList_Filter(object sender, FilterEventArgs e)
        {
            // Set e.Accepted to true to include the item in the list
            if (!onlyJoans)
                e.Accepted = true;
            else
            {
                Actor a = e.Item as Actor;
                e.Accepted = (a.FirstName == "Joan") ? true : false;
            }
        }

986-001
986-002

We also have to make sure to “refresh” the CollectionViewSource when the OnlyJoans property changes.  This will trigger it to re-filter the collection.

        private bool onlyJoans;
        public bool OnlyJoans
        {
            get { return onlyJoans; }
            set
            {
                if (value != onlyJoans)
                {
                    onlyJoans = value;
                    RaisePropertyChanged("OnlyJoans");
                    ((CollectionViewSource)this.Resources["cvsActors"]).View.Refresh();
                }
            }
        }

About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

3 Responses to #986 – Filtering a ListBox Using a CollectionViewSource

  1. Pingback: #989 – Enabling Live Filtering in a CollectionViewSource | 2,000 Things You Should Know About WPF

  2. Roger Schlueter says:

    In .NET 4.6.2 (the version I attempted to use this approach on) Filter is not a direct property of a CollectionViewSource. Rather, I used the following code-behind snippet, where “cvs” is a CollectionViewSource defined in XAML:

    Dim cvs As CollectionViewSource = DirectCast(Resources(“”), CollectionViewSource)
    AddHandler cvs.Filter, AddressOf

    • Sean says:

      The example in this post does work just fine in 4.6.2. Note that Filter was never a property of CollectionViewSource. It’s an event and in my code-behind example, I’m attaching a handler to it. It looks like you’re doing the same thing, only in VB.NET rather than C#.

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