[BUG] Unable to add localization for .NET MAUI app in VS Code on macOS due to the missing *.resx support

[mariuszmatusiak]

Describe the Issue

I am creating a .NET MAUI application on macOS (M1 Pro) in VS Code (due to the recently dropped support for Visual Studio for Mac).
I followed the official documentation https://learn.microsoft.com/en-us/dotnet/maui/fundamentals/localization?view=net-maui-8.0 but since not using Visual Studio I was forced to add the *.resx file manually. I figured out the format by using the resgen port available in Mono (version 6.12.0.0). Unfortunately though my compilation fails due to the "Undefined CLR namespace. The 'clr-namespace' URI refers to a namespace 'App.Resources.Languages' that could not be found." error thrown in the main page xaml definition
xmlns:strings="clr-namespace:App.Resources.Languages"
inside the ContentPage. After a thorough search, I then figured out that this might be due to the missing *.Designer.cs file which is normally generated by Visual Studio. I think resgen should also support its generation but the available Mono port version lacks this feature.
How can I proceed further in this case?

Redirected from the thread: dotnet/maui#25260 (comment)

Steps To Reproduce

1. Create a new .NET MAUI project with command line for Visual Studio Code
2. Follow the Localization guide in .NET MAUI documentation

Expected Behavior

Be able to create a proper *.resx file with *.cs code behind

Environment Information

macOS Sonoma v14.7
VS Code Version: 1.94.2 (Universal)
Commit: 384ff7382de624fb94dbaf6da11977bba1ecd427
Date: 2024-10-09T16:08:44.566Z
Electron: 30.5.1
ElectronBuildId: 10262041
Chromium: 124.0.6367.243
Node.js: 20.16.0
V8: 12.4.254.20-electron.0
OS: Darwin arm64 23.6.0
.NET MAUI Version: 8.0.91 SR9.1

[emaf]

This looks like a C# Dev Kit issue as there is no support for resx files for any project type.

[mariuszmatusiak]

I have finally found a workaround by adding these blocks in app's .csproj:

<EmbeddedResource Update="Resources\Languages\Locale.resx">
<Generator>MSBuild:Compile</Generator>
<StronglyTypedFileName>Resources\Languages\Locale.Designer.cs</StronglyTypedFileName>
<StronglyTypedLanguage>CSharp</StronglyTypedLanguage>
<StronglyTypedNamespace>App.Resources.Languages</StronglyTypedNamespace>
<StronglyTypedClassName>Locale</StronglyTypedClassName>
</EmbeddedResource>

<EmbeddedResource Update="Resources\Languages\Locale.pl-PL.resx">
<Generator>MSBuild:Compile</Generator>
<StronglyTypedFileName>Resources\Languages\Locale.pl-PL.Designer.cs</StronglyTypedFileName>
<StronglyTypedLanguage>CSharp</StronglyTypedLanguage>
<StronglyTypedNamespace>App.Resources.Languages</StronglyTypedNamespace>
<StronglyTypedClassName>Locale.pl-PL</StronglyTypedClassName>
</EmbeddedResource>

It solves the compiling problem but the app language is not changed to Polish (pl-PL), even if I explicitly set Polish as the default language for the MAUI app in the macOS settings.