Binding SelectedItem in a HierarchicalDataTemplate-applied WPF TreeView

Question

I have a data-bound TreeView and I want to bind SelectedItem. This attached behavior works perfectly without HierarchicalDataTemplate

Answer 1

I know this is old question, but perhaps it will be helpful for others. I combined a code from Link

And it looks now:

using System.Windows;
using System.Windows.Controls;
using System.Windows.Interactivity;
using System.Windows.Media;

namespace Behaviors
{
    public class BindableSelectedItemBehavior : Behavior
    {
        #region SelectedItem Property

        public object SelectedItem
        {
            get { return (object)GetValue(SelectedItemProperty); }
            set { SetValue(SelectedItemProperty, value); }
        }

        public static readonly DependencyProperty SelectedItemProperty =
            DependencyProperty.Register("SelectedItem", typeof(object), typeof(BindableSelectedItemBehavior), new UIPropertyMetadata(null, OnSelectedItemChanged));

        private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        {
            // if binded to vm collection than this way is not working
            //var item = e.NewValue as TreeViewItem;
            //if (item != null)
            //{
            //    item.SetValue(TreeViewItem.IsSelectedProperty, true);
            //}

            var tvi = e.NewValue as TreeViewItem;
            if (tvi == null)
            {
                var tree = ((BindableSelectedItemBehavior)sender).AssociatedObject;
                tvi = GetTreeViewItem(tree, e.NewValue);
            }
            if (tvi != null)
            {
                tvi.IsSelected = true;
                tvi.Focus();
            }
        }

        #endregion

        #region Private

        private void OnTreeViewSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs