Persist the Selection of the RadGridView when it is Paged
Environment
| Product | RadGridView for WPF |
Description
How to save and restore the selection in a RadGridView when a RadDataPager is used for paging.
Solution
Handle the PageIndexChanging event in order to save the selection for the current page and the PageIndexChanged event in order to restore it. Example 1 demonstrates some sample logic for how this can be achieved.
Example 1: Custom Behavior with logic for persisting the RadGridView selection
public class PersistSelectionBehavior : Behavior<RadDataPager>
{
public static void SetTargetGrid(DependencyObject obj, object value)
{
obj.SetValue(TargetGridProperty, value);
}
public static readonly DependencyProperty TargetGridProperty =
DependencyProperty.RegisterAttached("TargetGrid", typeof(object), typeof(PersistSelectionBehavior), new PropertyMetadata(null));
protected override void OnAttached()
{
base.OnAttached();
this.AssociatedObject.PageIndexChanging += Pager_PageIndexChanging;
this.AssociatedObject.PageIndexChanged += Pager_PageIndexChanged;
}
protected override void OnDetaching()
{
base.OnDetaching();
this.AssociatedObject.PageIndexChanging -= Pager_PageIndexChanging;
this.AssociatedObject.PageIndexChanged -= Pager_PageIndexChanged;
}
public static object GetTargetGrid(DependencyObject obj)
{
return (object)obj.GetValue(TargetGridProperty);
}
public RadGridView PagedGrid
{
get
{
return this.GetValue(TargetGridProperty) as RadGridView;
}
}
private static Dictionary<int, List<object>> persistedSelectionPerPage = new Dictionary<int, List<object>>();
private void Pager_PageIndexChanging(object sender, PageIndexChangingEventArgs e)
{
if (!persistedSelectionPerPage.ContainsKey(e.OldPageIndex))
{
persistedSelectionPerPage[e.OldPageIndex] = new List<object>();
}
persistedSelectionPerPage[e.OldPageIndex].Clear();
foreach (var item in this.PagedGrid.SelectedItems)
{
persistedSelectionPerPage[e.OldPageIndex].Add(item);
}
}
private void Pager_PageIndexChanged(object sender, PageIndexChangedEventArgs e)
{
if (persistedSelectionPerPage.ContainsKey(e.NewPageIndex))
{
foreach (var item in persistedSelectionPerPage[e.NewPageIndex])
{
this.PagedGrid.SelectedItems.Add(item);
}
}
}
}
In order to utilize the Behavior class, you should add a reference to the "System.Windows.Interactivity" dll.
Example 2: RadGridView and RadDataPager setup in xaml
<Grid xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity">
<Grid.DataContext>
<my:MyViewModel />
</Grid.DataContext>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<telerik:RadGridView Name="clubsGrid"
ItemsSource="{Binding Clubs}"
AutoGenerateColumns="False"
GroupRenderMode="Flat"
SelectionMode="Multiple"
EnableLostFocusSelectedState ="False">
<telerik:RadGridView.Columns>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Name}"/>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Established}"
Header="Est."
DataFormatString="{}{0:yyyy}"/>
<telerik:GridViewDataColumn DataMemberBinding="{Binding StadiumCapacity}"
Header="Stadium"
DataFormatString="{}{0:N0}"/>
</telerik:RadGridView.Columns>
</telerik:RadGridView>
<telerik:RadDataPager x:Name="radDataPager"
Source="{Binding Items, ElementName=clubsGrid}"
PageSize="5"
Grid.Row="1">
<i:Interaction.Behaviors>
<my:PersistSelectionBehavior TargetGrid="{Binding ElementName=clubsGrid}" />
</i:Interaction.Behaviors>
</telerik:RadDataPager>
</Grid>
The "my" namespace refers to the namespace where the "PersistSelectionBehavior" class is defined.