Selelect ListBoxItem when focus TextBox inside ItemTemplate

[workgroupengineering]

Considering following code:

	<StackPanel>
		<TextBlock Text="{Binding Greeting}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
		<ListBox ItemsSource="{Binding  Items}">
			<ListBox.ItemTemplate>
				<DataTemplate>
					<TextBox Text="{Binding Name}"
							   Margin="5"/>
				</DataTemplate>
			</ListBox.ItemTemplate>
		</ListBox>
	</StackPanel>

I would like the ListBoxItem to be selected when activating the Textbox. How can I do?

Avalonia Version: 11.0.0-preview7

At.zip

[timunie]

You could use an EventHandler for TextBox.GotFocus which sets SelectedItem on parent ListBox like this:

! <!-- Do NOT place ListBox inside StackPanel as it will break virtualization -->
<DockPanel LastChildFill="True">
    <TextBlock Text="{Binding Greeting}" 
               DockPanel.Dock="Top"/>
    <ListBox ItemsSource="{Binding  Items}">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <TextBox Text="{Binding Name}"
+                        GotFocus="TextBox_OnGotFocus"
                         Margin="5"/>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
</DockPanel>

and in the event handler:

private void TextBox_OnGotFocus(object? sender, GotFocusEventArgs e)
{
    // Test if the sender is a TextBox. If so, try to find an ancestor of type ListBox
    if (sender is TextBox tb && tb.FindAncestorOfType<ListBox>() is { } lb)
    {
        // Set the selected item of our ListBox to the DataContext of our TextBox
        lb.SelectedItem = tb.DataContext;
    }
}

Note: If you want this to be applied in several places, you can also wirte a behavior which can be attached easily.

[gmccardle]

I ran into this problem and creating an attached property for this. I figure it might be useful to someone else:

using Avalonia;
using Avalonia.Controls;
using Avalonia.Data;
using Avalonia.Input;
using Avalonia.Interactivity;
using Avalonia.VisualTree;

namespace AttachedProperties
{
    /// <summary>
    /// Attached property for control that are insided a selectable control and need to have
    /// pointer pressed events handled by parent first.
    /// E.g. A TextBox inside of a ListBoxItem. Enabling this will allow the selection to
    /// on the ListBox to update when clicking on the Textbox.
    /// </summary>
    public class PointerPressedToSelectableParent
    {
        static PointerPressedToSelectableParent()
        {
            EnableProperty.Changed.AddClassHandler<Control>(HandleEnableChanged);
        }
        public static readonly AttachedProperty<bool> EnableProperty = AvaloniaProperty.RegisterAttached<PointerPressedToSelectableParent, Interactive, bool>("Enable", false, false, BindingMode.OneWay, null);

        public static bool GetEnable(AvaloniaObject obj) => obj.GetValue(EnableProperty);

        public static void SetEnable(AvaloniaObject obj, bool value) => obj.SetValue(EnableProperty, value);

        public static void HandleEnableChanged(Control element, AvaloniaPropertyChangedEventArgs args)
        {
            if (element is null)
                return;

            element.AddHandler(Control.PointerPressedEvent, PointerPressed, RoutingStrategies.Tunnel);
        }

        private static void PointerPressed(object? sender, PointerPressedEventArgs e)
        {
            if (sender is Control control)
            {
                ISelectable? parent = control.FindAncestorOfType<ISelectable>();
                if (parent is Control parentControl)
                {
                    // Push pointer event up to parent
                    parentControl.RaiseEvent(e);

                    // If parent is selected clear handled so control also responds to pointer event
                    if (parent.IsSelected)
                    {
                        e.Handled = false;
                    }

                    // Otherwise, disable and re-enable control to clear its focus (row is deselected on click, likely by control click in multi-select mode)
                    else if (control.IsEnabled)
                    {
                        control.IsEnabled = false;
                        control.IsEnabled = true;
                    }
                }

                // Handle DataGrid
                else if (control.Parent is DataGridCell cell)
                {
                    DataGridRow? row = control.FindAncestorOfType<DataGridRow>();
                    if (row is not null)
                    {
                        // Push pointer event up to parent
                        cell.RaiseEvent(e);

                        // If row is selected clear handled and refocus on control (above cell event handler always clears focus)
                        if (row.IsSelected)
                        {
                            e.Handled = false;
                            control.Focus();
                        }
                    }
                }
            }
        }
    }
}

Which can be attached in xaml:

<ListBox ItemsSource="{Binding Items}" SelectionMode="Multiple">
     <ListBox.ItemTemplate>
         <DataTemplate>
             <TextBox Text="{Binding Value}" ap:PointerPressedToSelectableParent.Enable="True" />
         </DataTemplate>
     </ListBox.ItemTemplate>
</ListBox>

Still seems a bit weird to me that this is needed for some control (e.g. TextBox), but not other (e.g. ComboBox).