TreeView does not respect initial SelectedItem when initialized

[AndrewKeepCoding]

Describe the bug

I created a reproducible project here but is something like the following:

public partial class ShellViewModel : ObservableObject
{
    [ObservableProperty]
    private string[] _items =
        [
            "Item 1",
            "Item 2",
            "Item 3",
        ];

    [ObservableProperty]
    private string? _selectedItem;

    public ShellViewModel()
    {
        SelectedItem = Items[1];
    }

    [RelayCommand]
    private void SelectFirstItem() => SelectedItem = Items.First();

    [RelayCommand]
    private void SelectLastItem() => SelectedItem = Items.Last();
}

<ListView
    ItemsSource="{x:Bind ViewModel.Items}"
    SelectedItem="{x:Bind ViewModel.SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<GridView
    ItemsSource="{x:Bind ViewModel.Items}"
    SelectedItem="{x:Bind ViewModel.SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<NavigationView
    MenuItemsSource="{x:Bind ViewModel.Items}"
    SelectedItem="{x:Bind ViewModel.SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<TreeView
    ItemsSource="{x:Bind ViewModel.Items}"
    SelectedItem="{x:Bind ViewModel.SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />

As you can see, the TreeView control is not respecting the bound SelectedItem right after it's initialized. It should have "Item 2" selected. And you can also see that the binding is not broken.

20241030-1431-52.8086650.mp4

Steps to reproduce the bug

Use the repo above.

Expected behavior

TreeView respects SelectedItem when loaded.

Screenshots

No response

NuGet package version

WinUI 3 - Windows App SDK 1.6.1: 1.6.240923002

Windows version

Windows Insider Build (xxxxx)

Additional context

No response

[ghost1372]

I think this is happening because the treeview control is not loaded yet!

Therefore, instead of setting the selectedItem in the constructor, set it in the page loaded event

[AndrewKeepCoding]

Your sample project link is broken...

Sorry about that. Fixed the link.

I think this is happening because the treeview control is not loaded yet!
Therefore, instead of setting the selectedItem in the constructor, set it in the page loaded event

The SelectedItem is not set in the constructor, it's just bound to a property in the view model. ListView, GridView and NavigationView are under the same state but only the TreeView doesn't select the bound item.

[AndrewKeepCoding]

I understand that they are different controls, but I think they should have consistency on basic behaviors.

[ghost1372]

Your sample project link is broken...

Sorry about that. Fixed the link.

I think this is happening because the treeview control is not loaded yet!
Therefore, instead of setting the selectedItem in the constructor, set it in the page loaded event

The SelectedItem is not set in the constructor, it's just bound to a property in the view model. ListView, GridView and NavigationView are under the same state but only the TreeView doesn't select the bound item.

Loaded event working fine for me!

private void Page_Loaded(object sender, Microsoft.UI.Xaml.RoutedEventArgs e)
{
    ViewModel.init();
}

public void init()
{
    SelectedItem = Items[1];
}

[ghost1372]

[AndrewKeepCoding]

Thanks for confirming it but I guess the TreeView control should have the same basic behaviors as the other controls.

[ghost1372]

Thanks for confirming it but I guess the TreeView control should have the same basic behaviors as the other controls.

Therefore you should create a new issue and mentation that ctor is not working in treeview