using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Collections.ObjectModel;

namespace RadTreeViewSample

{

    class Level

    {

        public Level(int id, string name, Level parentLevel)

        {

            this.ID = id;

            this.Name = name;

            this.ParentLevel = parentLevel;

        }

        public int ID { get; set; }

        public string Name { get; set; }

        public Level ParentLevel { get; set; }

        public ObservableCollection<Level> ChildLevels { get; set; }

        public static ObservableCollection<Level> SampleLevelList(int level, Level parentOrg)

        {

            ObservableCollection<Level> orgList = new ObservableCollection<Level>();

            for (int i = 0; i < 5; i++)

            {

                Level org = new Level(i, "Level " + level.ToString() + "-" + i.ToString(), parentOrg);

                if (level > 0)

                    org.ChildLevels = SampleLevelList(level - 1, org);

                orgList.Add(org);

            }

            return orgList;

        }

    }

}

Here is the xaml

<Window x:Class="RadTreeViewSample.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

        xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"

        xmlns:telerikTV="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.Navigation"

        Title="MainWindow" Height="350" Width="525">

    <Window.Resources>

        <HierarchicalDataTemplate x:Key="items" ItemsSource="{Binding ChildLevels}">

            <TextBlock Text="{Binding Name}"/>

        </HierarchicalDataTemplate>

    </Window.Resources>

    <Grid>

        <Grid.RowDefinitions>

            <RowDefinition Height="auto"/>

            <RowDefinition />

        </Grid.RowDefinitions>

        <Grid.ColumnDefinitions>

            <ColumnDefinition />

            <ColumnDefinition Width="auto"/>

        </Grid.ColumnDefinitions>

        <TextBox x:Name="txtOrgname" Grid.Row="0" Grid.Column="0" Margin="5" />

        <Button x:Name="btnSearch" Content="Search" Width="80" Grid.Row="0" Grid.Column="1" Margin="5" Click="btnSearch_Click"/>

        <telerik:RadTreeView x:Name="rtvLevel" ItemTemplate="{StaticResource items}" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" Margin="5"/>

    </Grid>

</Window>

Here is my code-behind

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Shapes;

using System.Collections.ObjectModel;

namespace RadTreeViewSample

{

    /// <summary>

    /// Interaction logic for MainWindow.xaml

    /// </summary>

    public partial class MainWindow : Window

    {

        private ObservableCollection<Level> LevelList;

        public MainWindow()

        {

            InitializeComponent();

            ObservableCollection<Level> LevelList = Level.SampleLevelList(5, null);

            rtvLevel.ItemsSource = LevelList;

        }

        private void btnSearch_Click(object sender, RoutedEventArgs e)

        {

What should I write here to filter the LevelList, so that only element that contains search string are show

       in treeview with their upper hierarchy only upto root ?

        }

    }

}