#988 – Enabling Live Sorting in a CollectionViewSource

By default, when you’re using a CollectionViewSource to do sorting, grouping and filtering in a list-based control, the sorting/grouping/filtering behavior will only updated when you explicitly refresh the CollectionViewSource (by calling Refresh) or when you add or remove something to the collection.

You can enable live sorting in the CollectionViewSource to cause it to resort items when one or more properties on the bound objects change.  In the example below, we set the IsLiveSortingRequested property to true and specify that the Actor.LastName property is the property to live sort on.

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

Now when we make a change to the last name of one of the actors, the sorting is updated.

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#987 – CollectionViewSource Updates on Refresh or Change to Collection

By default, when you’re using a CollectionViewSource to do sorting, grouping and filtering in a list-based control, the sorting/grouping/filtering behavior will only updated when you explicitly refresh the CollectionViewSource (by calling Refresh) or when you add or remove something to the collection.

For example, if we add an actor to a list of actors and we are sorting by last name, the actor will be inserted at the correct spot.

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If you change the contents of one of the bound objects, however, the sorting behavior is not updated.  For example, if we change the last name of “Jennifer Jones” to “Garner” and we do not call the Refresh method of the CollectionViewSource, the sorting will be wrong.

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#983 – Using a CollectionViewSource to Sort Items in a ListBox

You can sort items within a ListBox using a CollectionViewSource, which is a wrapper around a view of a collection.  The CollectionViewSource provides support for sorting, filtering and grouping items in the underlying collection.  It provides a mechanism for configuring the view from XAML.

In the example below, we define a CollectionViewSource that wraps a collection of Actor objects and specifies a property to sort on (the actor’s last name).  Our ListBox then binds to the CollectionViewSource rather than to the collection.

    <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="190"
                 ItemsSource="{Binding Source={StaticResource cvsActors}}"/>
    </StackPanel>

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The Actor objects in our ListBox are now sorted by their LastName. (LastName is a property of the Actor object).
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