UWP TreeView Example demonstating Data Binding throws a Win32 Exception.

Question

There is a UWP TreeView example in the Microsoft documentation at:

https://learn.microsoft.com/en-us/windows/uwp/design/controls-and-patterns/tree-view

I cannot get this example to run without getting an exception every time I try and select a checkbox.
The exception reads: An unhandled win32 exception occurred in [20652] TreeViewDemo.exe.
I am not able to debug this exception or continue.

I have included my source in a text file attachment.

22430-msquestion.txt

Answer 1

Hi,
instead of using Microsoft.UI.Xaml.Controls use Windows.UI.Xaml.Controls and Windows Version 17763 or higher. Try following demo:

XAML

And code:

using System.Collections.ObjectModel;  
using Windows.UI.Xaml;  
using Windows.UI.Xaml.Controls;  
  
// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409  
  
namespace App17  
{  
  /// <summary>  
  /// An empty page that can be used on its own or navigated to within a Frame.  
  /// </summary>  
  public sealed partial class Page17 : Page  
  {  
    private ObservableCollection<Item> DataSource = new ObservableCollection<Item>();  
  
    public Page17()  
    {  
      this.InitializeComponent();  
      DataSource = GetDessertData();  
    }  
  
    private ObservableCollection<Item> GetDessertData()  
    {  
      var list = new ObservableCollection<Item>();  
  
      Item flavorsCategory = new Item()  
      {  
        Name = "Flavors",  
        Children =  
                    {  
                        new Item() { Name = "Vanilla" },  
                        new Item() { Name = "Strawberry" },  
                        new Item() { Name = "Chocolate" }  
                    }  
      };  
  
      Item toppingsCategory = new Item()  
      {  
        Name = "Toppings",  
        Children =  
                    {  
                        new Item()  
                        {  
                            Name = "Candy",  
                            Children =  
                            {  
                                new Item() { Name = "Chocolate" },  
                                new Item() { Name = "Mint" },  
                                new Item() { Name = "Sprinkles" }  
                            }  
                        },  
                        new Item()  
                        {  
                            Name = "Fruits",  
                            Children =  
                            {  
                                new Item() { Name = "Mango" },  
                                new Item() { Name = "Peach" },  
                                new Item() { Name = "Kiwi" }  
                            }  
                        },  
                        new Item()  
                        {  
                            Name = "Berries",  
                            Children =  
                            {  
                                new Item() { Name = "Strawberry" },  
                                new Item() { Name = "Blueberry" },  
                                new Item() { Name = "Blackberry" }  
                            }  
                        }  
                    }  
      };  
  
      list.Add(flavorsCategory);  
      list.Add(toppingsCategory);  
      return list;  
    }  
  
    private void OrderButton_Click(object sender, RoutedEventArgs e)  
    {  
      FlavorList.Text = string.Empty;  
      ToppingList.Text = string.Empty;  
  
      foreach (TreeViewNode node in DessertTree.SelectedNodes)  
      {  
        if (node.Parent.Content?.ToString() == "Flavors")  
        {  
          FlavorList.Text += node.Content + "; ";  
        }  
        else if (node.HasChildren == false)  
        {  
          ToppingList.Text += node.Content + "; ";  
        }  
      }  
    }  
  
    private void SelectAllButton_Click(object sender, RoutedEventArgs e)  
    {  
      if (DessertTree.SelectionMode == TreeViewSelectionMode.Multiple)  
      {  
        DessertTree.SelectAll();  
      }  
    }  
  }  
  
  public class Item  
  {  
    public string Name { get; set; }  
    public ObservableCollection<Item> Children { get; set; } = new ObservableCollection<Item>();  
  
    public override string ToString()  
    {  
      return Name;  
    }  
  }  
}