ApplicationLanguages.PrimaryLanguageOverride doesn't update x:Uid without restarting the app

[YegorStepanov]

Describe the bug
After setting ApplicationLanguages.PrimaryLanguageOverride, the new pages use old x:Uid. Restart only refresh it. The code below updates x:Uid in UWP but doesn't in WinUI.

The following sub-links also don't solve the problem:
UWP - Change of Languages

Are in WinUI the way to update x:Uid in runtime without manually updating strings in response to qualifier value change events?

Steps to reproduce the bug
Steps to reproduce the behavior:

1. Add "Hello.Text" to Strings/en/Resources.resw and to Strings/ru/Resources.resw
2. Assign x:Uid to TextBlock
3. Copy templated UWP code from OnLaunched and eliminate the errors (base.Frame is null by default in WinUI)
4. Add handler to button:

private void myButton_Click(object sender, RoutedEventArgs e)
{
    string lang = ApplicationLanguages.PrimaryLanguageOverride is "en" ? "ru" : "en";
    ApplicationLanguages.PrimaryLanguageOverride = lang;
        
    ResourceContext.GetForViewIndependentUse().Reset();
    
    Frame.Navigate(typeof(MainPage)); //old
    
    new Window { Content = new MainPage() }.Activate(); //old

    //it works, but not in XAML
    string newLanguage = ResourceLoader.GetForViewIndependentUse().GetString("Hello/Text");
}

Expected behavior
The newly created Page/Window has the desired localizated x:Uid.

Version Info
[WinUI 3 - Windows App SDK 0.8: 0.8.0]
[WinUI 3 - Windows App SDK 1.0.0-preview1]

Windows app type:

UWP	Win32
	Yes

Windows version	Saw the problem?
Insider Build (22000)	Yes
May 2021 Update (19043)
October 2020 Update (19042)
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

[StephenLPeters]

@fabiant3 FYI

[quangtrang1111]

I also got this exception like below when run as Unpackage in version 1.0.
Anyone can help?

[StephenLPeters]

@MikeHillberg and @codendone FYI as well

[ynborokh]

@YegorStepanov @StephenLPeters Is it really a bug? According to the documentation:

When you set the PrimaryLanguageOverride, this is immediately reflected in the ApplicationLanguages.Languages property. However, this change may not take effect immediately on resources loaded in the app UI. To make sure the app responds to such changes, you can listen to the QualifierValues property on a default resource context and take whatever actions may be needed to reload resources. Those requirements may vary depending on the UI framework used by the app, and it may be necessary to restart the app.

[YegorStepanov]

As far as I know, WinUI 3 is a continuation of UWP, and if something doesn't work and there are no docs that say it deprecated/can't be applied, then it is bug.

Whether it's a bug or not, reloading the app to change the language is a bad UX.

[MichaelJachan]

Hello all!

I am starting now with WinUI 3 localization (Win10, Community Toolkit and WinUI 3 at the latest versions (as of July 2023). My .NET libraries are updating the newly set language at runtime:

CultureInfo.CurrentUICulture = new CultureInfo(newLanguage);

My WinUI 3 Projects do not; but it is updated on App restart:

ApplicationLanguages.PrimaryLanguageOverride = newLanguage;

I would like you @ynborokh to give us an example of

"listen to the QualifierValues property on a default resource context and take whatever actions may be needed to reload resources"

And i wonder (in my humble experience) why the at-runtime-WinUI3-Language-Update could not be an async Method(), that, once finished, has done all the resource-reloading?

Best, MJ:)

[JoeTomkinson]

Two years on and this still appears to be, assumeably, not a priority.

It's possible to spin up our own version of language resource management which can be applied appropriately upon language change to the relevant UI components; but that seems like a lot of work for something which probably should be handled the same way bindeable properties are updated across the UI layout.

I can't seem to find where microsoft-ui-xaml or the WinSDK resolve resw files, would be more than happy to take a look if someone can point me in the right direction.

[ghost1372]

@duncanmacmichael i tested with v1.6-exp2 and now we can use
Microsoft.Windows.Globalization.ApplicationLanguages.PrimaryLanguageOverride = "fa-IR";
and everything is working fine, and i think this issue can be closed

[codendone]

Thanks, @ghost1372!

Closing as fixed in 1.6.240701003-experimental2 via microsoft/WindowsAppSDK#4523.