When you bind to a data collection, you may want to sort, filter, or group the data. To do that, you use collection views. You can think of a CollectionView as the layer on top of the binding source collection that allows you to navigate and display the source collection based on sort, filter, and group queries, all without having to manipulate the underlying source collection itself. If the source collection implements the INotifyCollectionChanged interface, the changes raised by the CollectionChanged event are propagated to the views.

All collections have a default CollectionView. For all collections implementing IList, the ListCollectionView object is the default view object. The BindingListCollectionView is the collection view class used for collections that implement IBindingList. To get the default view, you use the GetDefaultView method. For an example, see How to: Get the Default View of a Data Collection.

For more information about collection views, see Data Binding Overview.

This example describes how to sort data in a view.

The following example creates a simple ListBox and a Button:

<Window x:Class="ListBoxSort_snip.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="ListBoxSort_snip" Height="300" Width="300">
    <DockPanel>
      <ListBox Name="myListBox" DockPanel.Dock="Top">
        <ListBoxItem>my</ListBoxItem>
        <!--Or you can set the content this way:-->
        <!--<ListBoxItem Content="my"/>-->
        <ListBoxItem>1</ListBoxItem>
        <ListBoxItem>Sort</ListBoxItem>
        <ListBoxItem>3</ListBoxItem>
        <ListBoxItem>ListBox</ListBoxItem>
        <ListBoxItem>2</ListBoxItem>
      </ListBox>
      <Button Click="OnClick" Width="30" Height="20" DockPanel.Dock="Top">Sort</Button>
    </DockPanel>
</Window>

The Click event handler of the button contains logic to sort the items in the ListBox in the descending order. You can do this because adding items to a ListBox this way adds them to the ItemCollection of the ListBox, and ItemCollection derives from the CollectionView class. If you are binding your ListBox to a collection using the ItemsSource property, you can use the same technique to sort.

private void OnClick(object sender, RoutedEventArgs e)
{
    myListBox.Items.SortDescriptions.Add(
        new SortDescription("Content", ListSortDirection.Descending));
}

As long as you have a reference to the view object, you can use the same technique to sort the content of other collection views. For an example of how to obtain a view, see How to: Get the Default View of a Data Collection. For another example, see How to: Sort a GridView Column When a Header Is Clicked. For more information about views, see Binding to Collections in Data Binding Overview.

For an example of how to apply sorting logic in Extensible Application Markup Language (XAML), see How to: Sort and Group Data Using a View in XAML.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

.NET Framework

Reference

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