TomRR.SourceGenerator.SettingsBinder 0.0.4

⚙️ SettingsBinder

A lightweight, zero-boilerplate Roslyn Source Generator that binds [Settings]-annotated classes directly to the .NET Options pattern.

✨ Features

• ✅ Automatic binding of settings from appsettings.json
• ✅ Strongly-typed settings via [Settings] attribute
• ✅ Supports IOptions<T>, validation, and DI
• ✅ Source-generated SectionName and registration logic
• ✅ Modular and customizable configuration pipelines
• ✅ Zero reflection, minimal runtime overhead
• ✅ XML Documentation

🚀 Quick Start

1. Install NuGet Package

dotnet add package TomRR.SourceGenerator.SettingsBinder

2. Define a Settings Class

using TomRR.SourceGenerator.SettingsBinder;

[Settings]
public sealed partial class LoggingSettings
{
    public string? Level { get; init; }
    public string? Format { get; init; }
}

3. Configure to appsettings.json

{
  "LoggingSettings": {
    "Level": "Information",
    "Format": "Json"
  }
}

4. Wire Up in Program.cs

var builder = WebApplication.CreateBuilder(args);

// ✅ Default configuration sources
builder.Configuration.AddDefaultConfigurationSources<Program>();

// ✅ Registers all [Settings] classes automatically
builder.AddSettingsOptions();

var app = builder.Build();

✅ You're done!

🧩 Advanced Configuration Pipeline

If you prefer fine-grained control over configuration sources:

builder.Configuration
    .WithBasePath()
    .WithJsonFile()
    .WithEnvironmentJsonFile()
    .WithSecrets<Program>()
    .WithEnvironmentVariables();

You can mix & match based on your project needs.

✅ What Gets Generated?

✅ Interface

public interface ISettings
{
    static abstract string SectionName { get; }
}

✅ Partial Class Implementation with SectionName

public sealed partial class LoggingSettings : ISettings
{
    public static string SectionName => "LoggingSettings";
}

✅ Default Configuration Sourcing

public static IConfigurationBuilder AddDefaultConfigurationSources<T>(this IConfigurationBuilder builder) where T : class 
    => builder
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
        .AddJsonFile("appsettings.Development.json", optional: true, reloadOnChange: true)
        .AddUserSecrets<T>()
        .AddEnvironmentVariables();

✅ Automatic Binding with Validation

builder.Services
    .AddOptions<LoggingSettings>()
    .Bind(builder.Configuration.GetSection(LoggingSettings.SectionName))
    .ValidateDataAnnotations()
    .ValidateOnStart();

🎛️ Customize Section Names

You can explicitly override the section name using the attribute:

[Settings("MyCustomSection")]
public sealed partial class AdvancedSettings
{
    public string? Mode { get; init; }
    public bool Enabled { get; init; }
}

This generates:

public sealed partial class AdvancedSettings : ISettings
{
    public static string SectionName => "MyCustomSection";
}

{
  "MyCustomSection": {
    "Mode": "Debug",
    "Enabled": true
  }
}

🧠 Use this when the config section does not match the class name.

🏆 Performance

SettingsBinder:

• ✅ Zero reflection at runtime (everything is compile-time generated).
• ✅ No ActivatorUtilities, no extra runtime DI overhead.
• ✅ Source generation ensures optimal performance with minimal allocations.

📦 Package Info

📄 License

Licensed under the Apache License 2.0.