Native.SourceGenerator.Configuration 1.0.3

Native.SourceGenerator.Configuration

AOT-first Source Generator for Configuration Binding - Binds configuration values (environment variables and appsettings.json) to fields without reflection or ConfigurationBinder.

Features

• ✅ 100% Native AOT Compatible - No reflection, no ConfigurationBinder
• ✅ Compile-time Binding Generation - All errors caught at build time
• ✅ Two Configuration Sources:
  • [EnvironmentConfig] - Read from environment variables
  • [AppSettings] - Read from appsettings.json (IConfiguration)
• ✅ Type-safe Configuration - Supports string, int, bool, double, decimal, TimeSpan, DateTime, Guid, Uri
• ✅ IIncrementalGenerator - Fast, incremental builds

Installation

dotnet add package Native.SourceGenerator.Configuration

Usage

Option 1: Using [EnvironmentConfig] for Environment Variables

Mark your class as partial and fields with [EnvironmentConfig]:

using Native.SourceGenerator.Configuration;

public partial class DatabaseSettings
{
    [EnvironmentConfig("DATABASE_URL")]
    private string _connectionString;
    public string ConnectionString => _connectionString;

    [EnvironmentConfig("MAX_CONNECTIONS", Required = false, DefaultValue = "100")]
    private int _maxConnections;
    public int MaxConnections => _maxConnections;

    [EnvironmentConfig("ENABLE_SSL", Required = false, DefaultValue = "true")]
    private bool _enableSsl;
    public bool EnableSsl => _enableSsl;
}

Option 2: Using [AppSettings] for appsettings.json

For configuration stored in appsettings.json, use the [AppSettings] attribute with the configuration key path:

appsettings.json:

{
    "Services": {
        "UrlBase": "http://localhost:3000",
        "Timeout": 30
    },
    "Database": {
        "ConnectionString": "Server=localhost;Database=mydb",
        "MaxPoolSize": 100
    },
    "Features": {
        "EnableNewDashboard": true
    }
}

C# Configuration Class:

using Native.SourceGenerator.Configuration;

public partial class ServiceSettings
{
    [AppSettings("Services:UrlBase")]
    private string _urlBase;
    public string UrlBase => _urlBase;

    [AppSettings("Services:Timeout", Required = false, DefaultValue = "60")]
    private int _timeout;
    public int Timeout => _timeout;

    [AppSettings("Database:ConnectionString")]
    private string _connectionString;
    public string ConnectionString => _connectionString;

    [AppSettings("Features:EnableNewDashboard", Required = false, DefaultValue = "false")]
    private bool _enableNewDashboard;
    public bool EnableNewDashboard => _enableNewDashboard;
}

Option 3: Mixing Both Attributes

You can use both attributes in the same class for hybrid configuration:

using Native.SourceGenerator.Configuration;

public partial class HybridSettings
{
    // From environment variable (typically secrets)
    [EnvironmentConfig("API_SECRET_KEY")]
    private string _secretKey;
    public string SecretKey => _secretKey;

    // From appsettings.json (application settings)
    [AppSettings("Api:BaseUrl")]
    private string _baseUrl;
    public string BaseUrl => _baseUrl;

    [AppSettings("Api:Timeout", Required = false, DefaultValue = "30")]
    private int _timeout;
    public int Timeout => _timeout;
}

Injecting Configuration

var configuration = new ConfigurationBuilder()
    .AddJsonFile("appsettings.json")
    .AddEnvironmentVariables()
    .Build();

var settings = new ServiceSettings();
settings.__InjectConfiguration(configuration);

Console.WriteLine($"URL Base: {settings.UrlBase}");
Console.WriteLine($"Timeout: {settings.Timeout}");

Generated Code

The generator creates an __InjectConfiguration method:

// Auto-generated
partial class ServiceSettings
{
    public void __InjectConfiguration(IConfiguration configuration)
    {
        _urlBase = configuration["Services:UrlBase"]
            ?? throw new InvalidOperationException("Missing required configuration: Services:UrlBase");

        _timeout = configuration["Services:Timeout"] is { Length: > 0 } __timeoutValue
            ? int.Parse(__timeoutValue)
            : int.Parse("60");

        _connectionString = configuration["Database:ConnectionString"]
            ?? throw new InvalidOperationException("Missing required configuration: Database:ConnectionString");

        _enableNewDashboard = configuration["Features:EnableNewDashboard"] is { Length: > 0 } __enableNewDashboardValue
            ? bool.Parse(__enableNewDashboardValue)
            : bool.Parse("false");
    }
}

Attribute Options

[EnvironmentConfig]

[AppSettings]

Supported Types

Nullable versions (int?, bool?, etc.) are also supported.

Diagnostics

Requirements

• .NET 10 SDK
• C# 13+
• Microsoft.Extensions.Configuration package
• Microsoft.Extensions.Configuration.Json package (for appsettings.json)
• Microsoft.Extensions.Configuration.EnvironmentVariables package (for environment variables)

License

MIT