Get Previous, Next, Parent and Sibling Node of a Specific TreeView Item
The RadTreeViewItem class exposes properties which allow you to access:
- Previous node
- Previous sibling node
- Next node
- Next sibling node
- Parent node
- Root node
Here is a simple treeview declaration:
<telerik:RadTreeView Margin="8" x:Name="radTreeView">
<telerik:RadTreeViewItem Header="Sport Categories">
<telerik:RadTreeViewItem Header="Football">
<telerik:RadTreeViewItem Header="Futsal"/>
<telerik:RadTreeViewItem Header="Soccer"/>
</telerik:RadTreeViewItem>
<telerik:RadTreeViewItem Header="Tennis">
<telerik:RadTreeViewItem Header="Table Tennis"/>
</telerik:RadTreeViewItem>
<telerik:RadTreeViewItem Header="Cycling">
<telerik:RadTreeViewItem Header="Road Cycling"/>
<telerik:RadTreeViewItem Header="Indoor Cycling"/>
<telerik:RadTreeViewItem Header="Mountain Bike"/>
</telerik:RadTreeViewItem>
</telerik:RadTreeViewItem>
</telerik:RadTreeView>
For example, you should attach to the SelectionChanged event and in the event handler get the selected items. Find the treeview declaration and add the following attribute:
<telerik:RadTreeView Margin="8" x:Name="radTreeView" SelectionChanged="radTreeView_SelectionChanged"> private void radTreeView_SelectionChanged( object sender, Telerik.Windows.Controls.SelectionChangedEventArgs e )
{
// Get a reference to the treeview
Telerik.Windows.Controls.RadTreeView treeView = sender as Telerik.Windows.Controls.RadTreeView;
// Get the currently selected items
ObservableCollection<Object> selectedItems = treeView.SelectedItems;
RadTreeViewItem item = selectedItems[ 0 ] as RadTreeViewItem;
}Accessing the PreviousItem and PreviousSiblingItem
When you want to get the previous item in the hierarchy (no matter the level) you need to use the PreviousItem property, while the PreviousSiblingItem property will return you the previous item on the same level. For example:
-
If you select the treeview item with header "Road Cycling", then the PreviousItem property will return you the treeview item with header "Cycling", while the PreviousSiblingItem property will return you null.
-
If you select the treeview item with header "Indoor Cycling", then both of the properties will return you the treeview item with header "Road Cycling".
private void radTreeView_SelectionChanged( object sender, Telerik.Windows.Controls.SelectionChangedEventArgs e )
{
// Get a reference to the treeview
Telerik.Windows.Controls.RadTreeView treeView = sender as Telerik.Windows.Controls.RadTreeView;
// Get the currently selected items
ObservableCollection<Object> selectedItems = treeView.SelectedItems;
RadTreeViewItem item = selectedItems[ 0 ] as RadTreeViewItem;
// Get the previous item and the previous sibling item
RadTreeViewItem previousItem = item.PreviousItem;
RadTreeViewItem previousSiblingItem = item.PreviousSiblingItem;
}Accessing the NextItem and NextSiblingItem
When you want to get the next item in the hierarchy (no matter the level) you need to use the NextItem property, while the NextSiblingItem property will return you the next item on the same level. For example:
-
If you select the treeview item with header "Soccer", then the NextItem property will return you the treeview item with header "Tennis", while the NextSiblingItem property will return you null.
-
If you select the treeview item with header "Futsal", then both of the properties will return you the treeview item with header "Soccer".
private void radTreeView_SelectionChanged( object sender, Telerik.Windows.Controls.SelectionChangedEventArgs e )
{
// Get a reference to the treeview
Telerik.Windows.Controls.RadTreeView treeView = sender as Telerik.Windows.Controls.RadTreeView;
// Get the currently selected items
ObservableCollection<Object> selectedItems = treeView.SelectedItems;
RadTreeViewItem item = selectedItems[ 0 ] as RadTreeViewItem;
// Get the previous item and the previous sibling item
RadTreeViewItem previousItem = item.PreviousItem;
RadTreeViewItem previousSiblingItem = item.PreviousSiblingItem;
// Get the next item and the next sibling item
RadTreeViewItem nextItem = item.NextItem;
RadTreeViewItem nextSiblingItem = item.NextSiblingItem;
} Private Sub radTreeView_SelectionChanged(ByVal sender As Object, ByVal e As Telerik.Windows.Controls.SelectionChangedEventArgs)
' Get a reference to the treeview '
Dim treeView As Telerik.Windows.Controls.RadTreeView = TryCast(sender, Telerik.Windows.Controls.RadTreeView)
' Get the currently selected items '
Dim selectedItems As ObservableCollection(Of [Object]) = treeView.SelectedItems
Dim item As RadTreeViewItem = TryCast(selectedItems(0), RadTreeViewItem)
' Get the previous item and the previous sibling item '
Dim previousItem As RadTreeViewItem = item.PreviousItem
Dim previousSiblingItem As RadTreeViewItem = item.PreviousSiblingItem
' Get the next item and the next sibling item '
Dim nextItem As RadTreeViewItem = item.NextItem
Dim nextSiblingItem As RadTreeViewItem = item.NextSiblingItem
End SubAccessing the ParentItem and RootItem
If you want to get the parent item of the currently selected item, you should use the ParentItem property. If you want to get the root item of the treeview, you should use the RootItem property. For example:
-
If you select the treeview item with header "Soccer", then the ParentItem property will return you the treeview item with header "Football", while the RootItem property will return you the treeview item with header "Sport Categories".
-
If you select the treeview item with header "Sport Categories", then the ParentItem property will return you null, while the RootItem property will return you the same treeview item (with header "Sport Categories").
private void radTreeView_SelectionChanged( object sender, Telerik.Windows.Controls.SelectionChangedEventArgs e )
{
// Get a reference to the treeview
Telerik.Windows.Controls.RadTreeView treeView = sender as Telerik.Windows.Controls.RadTreeView;
// Get the currently selected items
ObservableCollection<Object> selectedItems = treeView.SelectedItems;
RadTreeViewItem item = selectedItems[ 0 ] as RadTreeViewItem;
// Get the previous item and the previous sibling item
RadTreeViewItem previousItem = item.PreviousItem;
RadTreeViewItem previousSiblingItem = item.PreviousSiblingItem;
// Get the next item and the next sibling item
RadTreeViewItem nextItem = item.NextItem;
RadTreeViewItem nextSiblingItem = item.NextSiblingItem;
// Get the parent item and the root item
RadTreeViewItem parentItem = item.ParentItem;
RadTreeViewItem rootItem = item.RootItem;
}