Localizegen

Shiny Localization Generator Skill

You are an expert in Shiny.Extensions.Localization.Generator, a Roslyn incremental source generator that creates strongly-typed localization classes from .resx resource files for use with Microsoft.Extensions.Localization.

When to Use This Skill

Invoke this skill when the user wants to:

• Add localization/internationalization to a .NET application using .resx files
• Create strongly-typed localization wrappers around resource files
• Set up Microsoft.Extensions.Localization with generated code
• Add new .resx resource files with matching classes
• Use format string parameters in localized strings
• Configure public vs internal accessor generation
• Bind localized strings in XAML or Razor views with IntelliSense support

Library Overview

NuGet: Shiny.Extensions.Localization.Generator Namespace: Generated classes use the namespace derived from the project's RootNamespace and folder structure Target: .NET Standard 2.0 (works with any modern .NET application)

Shiny.Extensions.Localization.Generator is a Roslyn incremental source generator that:

• Reads .resx files at compile time and generates strongly-typed C# classes
• Creates properties for simple strings and methods for format strings (e.g., "Hello {0}")
• Generates a ServiceCollectionExtensions class with AddStronglyTypedLocalizations() for DI registration
• Supports XML documentation comments from .resx comment fields
• Respects folder structure for namespace computation
• Supports public or internal accessor generation via MSBuild property

Setup

1. Install NuGet Packages

dotnet add package Microsoft.Extensions.Localization
dotnet add package Shiny.Extensions.Localization.Generator

2. Register in DI

builder.Services.AddLocalization();
builder.Services.AddStronglyTypedLocalizations();

Important Notes

• Every .resx file must have a corresponding C# class with the same name in the same namespace (e.g., MyViewModel.resx requires MyViewModel.cs)
• If the associated class does not exist, the generated code will produce a compile error
• Only the default locale .resx file is processed (e.g., MyViewModel.resx), locale-specific files like MyViewModel.fr-ca.resx are handled by the localization framework at runtime
• The generator produces a {ClassName}Localized class (e.g., MyViewModelLocalized) for each .resx file

How It Works

Directory Structure

MyApp/
├── MyViewModel.cs
├── MyViewModel.resx              # Default locale (English)
├── MyViewModel.fr-ca.resx        # French-Canadian locale
├── Folder1/
│   ├── FolderViewModel.cs
│   ├── FolderViewModel.resx
│   └── FolderViewModel.fr-ca.resx

Generated Output

MyApp/
├── MyViewModelLocalized.g.cs                    # RootNamespace.MyViewModelLocalized
├── Folder1.FolderViewModelLocalized.g.cs        # RootNamespace.Folder1.FolderViewModelLocalized
├── ServiceCollectionExtensions.g.cs             # DI registration extension method

Resource Key Rules

• Dots (.), hyphens (-), and spaces in resource keys are converted to underscores (_)
• Format string parameters like {0}, {1} are detected automatically
• When format parameters are present, a method is generated instead of a property
• Method names get a Format suffix unless the key already ends with Format

Code Generation Instructions

When working with this library:

1. Resource Files (.resx)

Create .resx files alongside their associated C# class:

<?xml version="1.0" encoding="utf-8"?>
<root>
  <data name="Welcome" xml:space="preserve">
    <value>Welcome to our app!</value>
    <comment>Greeting shown on the home page</comment>
  </data>
  <data name="UserGreeting" xml:space="preserve">
    <value>Hello {0}, welcome to {1}!</value>
    <comment>Personalized greeting with user name and app name</comment>
  </data>
  <data name="ItemCount" xml:space="preserve">
    <value>You have {0} items in your cart</value>
  </data>
</root>

2. Associated Class

The class must exist with the same name and namespace as the .resx file:

namespace MyApp;

public class MyViewModel
{
    public MyViewModel(MyViewModelLocalized localizer)
    {
        this.Localizer = localizer;
    }

    public MyViewModelLocalized Localizer { get; }
}

3. Generated Class Structure

The generator creates:

namespace MyApp;

public partial class MyViewModelLocalized
{
    readonly IStringLocalizer localizer;

    public MyViewModelLocalized(IStringLocalizer<MyViewModel> localizer)
    {
        this.localizer = localizer;
    }

    public IStringLocalizer Localizer => this.localizer;

    /// <summary>
    /// Greeting shown on the home page
    /// </summary>
    public string Welcome => this.localizer["Welcome"];

    /// <summary>
    /// Personalized greeting with user name and app name
    /// </summary>
    public string UserGreetingFormat(object parameter0, object parameter1)
    {
        return string.Format(this.localizer["UserGreeting"], parameter0, parameter1);
    }

    /// <summary>
    /// You have {0} items in your cart
    /// </summary>
    public string ItemCountFormat(object parameter0)
    {
        return string.Format(this.localizer["ItemCount"], parameter0);
    }
}

4. XAML Binding

Bind in XAML with full IntelliSense:

<Label Text="{Binding Localizer.Welcome}" />

5. File Organization

Place files following standard .NET conventions:

• Resource files: alongside their associated class file
• Locale variants: same location with locale suffix (e.g., MyClass.fr-ca.resx)
• Folder structure determines namespace: Folder1/MyClass.resx → RootNamespace.Folder1

Configuration

Internal Accessor

To generate classes with internal instead of public access modifier:

<PropertyGroup>
    <GenerateLocalizersInternal>True</GenerateLocalizersInternal>
</PropertyGroup>

Usage Examples

Simple property access:

var localizer = services.GetRequiredService<MyViewModelLocalized>();
Console.WriteLine(localizer.Welcome);

Format string method:

Console.WriteLine(localizer.UserGreetingFormat("Allan", "MyApp"));
// Output: Hello Allan, welcome to MyApp!

XAML binding in MAUI:

<Label Text="{Binding Localizer.Welcome}" />

ASP.NET/Blazor usage:

@inject MyViewModelLocalized Localizer

<h1>@Localizer.Welcome</h1>
<p>@Localizer.UserGreetingFormat(User.Name, "MyApp")</p>

Best Practices

1. Always create the associated class - Every .resx file must have a matching C# class or a compile error will occur
2. Use comments in .resx - Comments become XML documentation on generated properties/methods
3. Use format parameters for dynamic content - {0}, {1} etc. generate type-safe methods
4. Use default locale for generation - Only ClassName.resx is processed; ClassName.fr-ca.resx is for runtime localization
5. Inject the Localized class - Use DI to inject {ClassName}Localized, not IStringLocalizer directly
6. Expose the raw localizer - The generated class exposes Localizer property for edge cases needing IStringLocalizer
7. Namespace follows folder structure - Organize .resx files in folders to match your namespace conventions

Reference Files

For detailed templates and examples, see:

• reference/templates.md - Code generation templates for common patterns
• reference/api-reference.md - Full API surface, MSBuild properties, and troubleshooting

Common Packages

dotnet add package Shiny.Extensions.Localization.Generator    # Source generator
dotnet add package Microsoft.Extensions.Localization           # Localization framework
dotnet add package Microsoft.Extensions.DependencyInjection    # DI container