ConfigTransformer 1.1.2

ConfigTransformer

ConfigTransformer is a .NET extension that enhances your configuration pipeline by transforming placeholders in your configuration values using the IConfigurationBuilder. It replaces tokens like {Settings:Api:BaseUrl} with their actual values from the configuration at runtime.

Ideal for simplifying complex, cross-referenced config structures in .NET apps (e.g., appsettings.json, environment variables, etc.).

✨ Features

• 🔁 Recursively replaces tokens like {Section:Sub:Key}
• 🔍 Deep traversal of the configuration structure
• ✅ Safe fallback for missing keys
• 🔄 Prevents infinite substitution loops
• 🛠️ Works directly on IConfigurationBuilder

📦 Usage

🔧 appsettings.json:

{
  "Settings": {
    "Api": {
      "BaseUrl": "https://api.example.com"
    }
  },
  "MyService": {
    "Endpoint": "{Settings:Api:BaseUrl}/v1/data"
  }
}

🌐 .NET App Initialization:

 builder.Configuration
     .SetBasePath(Directory.GetCurrentDirectory())
     .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
     .AddJsonFile($"appsettings.{builder.Environment.EnvironmentName}.json", optional: true)
     .AddEnvironmentVariables()
     .Transform(); // Replace all placeholders after config is loaded

✅ Output after Transform

"MyService": {
  "Endpoint": "https://api.example.com/v1/data"
}

🔄 How Placeholder Replacement Works

• Transform() scans all key-value pairs in the config.
• If a value contains {Some:Key}, it attempts to resolve Some:Key from the current configuration.
• It supports nested or chained placeholders.
• Up to 10 recursive passes are performed to ensure all placeholders are resolved.
• If a placeholder cannot be resolved, it is left untouched.

📌 Best Practices

• Call Transform() after your IConfigurationBuilder has loaded all sources.
• Do not use circular placeholders – transformation is capped at 10 recursive passes.
• Escape { and } with {{ or }} if you want them to remain literal.

📦 Installation

Install via NuGet

dotnet add package ConfigTransformer

Or via the NuGet Package Manager Console

Install-Package ConfigTransformer

📄 License

This project is licensed under the MIT License