FindName does not work on elements that are not in visual tree

[MartinZikmund]

Current behavior

string rootPanelXaml =
    @"<StackPanel xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
            <Button x:Name='button' Content='button'>
                <Button.KeyboardAccelerators>
                    <KeyboardAccelerator x:Name='keyboardAccelerator' Modifiers='Control' Key='A' />
                </Button.KeyboardAccelerators>
            </Button>
            <ContentDialog x:Name='dialog'>
                <Button x:Name='dialogButton'>DialogButton</Button>
            </ContentDialog>
        </StackPanel>";

var rootPanel = (StackPanel)XamlReader.Load(rootPanelXaml);
var button = (Button)rootPanel.FindName("button");

In case of Uno, button is null

Expected behavior

In WinUI,. button is set correctly.

How to reproduce it (as minimally and precisely as possible)

No response

Workaround

No response

Works on UWP/WinUI

Yes

Environment

No response

NuGet package version(s)

No response

Affected platforms

WebAssembly, Android, iOS, Mac Catalyst, Skia (WPF), Skia (Linux X11), Skia (macOS), Skia (Linux Framebuffer), Skia (GTK), Windows (WinAppSDK)

IDE

Visual Studio 2022

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

No response

[Youssef1313]

That should be because XamlReader doesn't support x:Name. Using Name instead can work as a workaround

[MartinZikmund]

Unfortunately this is not enough - in case of KeyboardAccelerator for example, it is a plain DO and it seems that because of it, neither Name or x:Name works in this case

[Youssef1313]

Ah. For non-FrameworkElements, FindName is impossible to get working without proper NameScope support. 😕

Draft PR: #16177, not very trivial one to get green though. It'll take a bit of time.

[MartinZikmund]

Scenario to validate/test against:

XamlReader.Load:

<StackPanel xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
    <Button x:Name='focusButton' Content='Click for Button Flyout'>
        <Button.ContextFlyout>
            <Flyout x:Name='ButtonFlyout'>
                <StackPanel x:Name='flyoutStackPanel'>
                   <Button x:Name='flyoutButton1' Content='flyoutButton1'>
                        <Button.KeyboardAccelerators>
                            <KeyboardAccelerator x:Name='flyoutAccelerator1' Modifiers='Control' Key='Number1' />
                        </Button.KeyboardAccelerators>
                   </Button>
                </StackPanel>
            </Flyout>
        </Button.ContextFlyout>
    </Button>
</StackPanel>

Test FindName:

• ButtonFlyout
• flyoutButton1
• focusButton
• flyoutAccelerator1

All should be non-null