Enviro #

A build_runner compatible package that generates type-safe environment configuration from .env files with multi-environment support for Flutter and Dart applications.

✨ Features #

• 🔒 Type-safe environment variable access
• 🌍 Multi-environment support (development, staging, production, etc.)
• 🚀 Build-time code generation with build_runner
• 📝 Automatic validation of pubspec.yaml assets configuration
• 🔄 Fallback mechanism - missing keys fall back to DEFAULT environment
• 🎯 Smart type detection (String, int, bool, double)
• 📦 Zero runtime dependencies - pure Dart/Flutter
• ⚡ Caching for optimal performance
• 🛡️ Error handling with helpful messages

🚀 Getting Started #

Prerequisites #

• Dart SDK >=3.0.0
• Flutter SDK (for Flutter projects)
• build_runner package

Installation #

Add enviro to your pubspec.yaml:

dependencies:
  enviro: ^0.0.1

dev_dependencies:
  build_runner: ^2.4.0

Then run:

flutter pub get

📖 Usage #

1. Create Environment Files #

Create .env files in your project root:

.env (required - default environment):

API_URL=https://api.example.com
DATABASE_URL=postgres://localhost:5432/production
DEBUG=false
PORT=3000
SECRET_KEY=your-secret-key
ENVIRONMENT=production
LOG_LEVEL=error

.env-development:

API_URL=https://api-dev.example.com
DATABASE_URL=postgres://localhost:5432/development
DEBUG=true
PORT=3001
SECRET_KEY=dev-secret-key
ENVIRONMENT=development
LOG_LEVEL=debug

.env-staging:

API_URL=https://api-staging.example.com
DATABASE_URL=postgres://localhost:5432/staging
DEBUG=false
PORT=3002
SECRET_KEY=staging-secret-key
ENVIRONMENT=staging
LOG_LEVEL=info

2. Add to pubspec.yaml Assets #

Add your .env files to pubspec.yaml:

flutter:
  assets:
    - .env
    - .env-development
    - .env-staging

Or use wildcard:

flutter:
  assets:
    - .env*

3. Generate Code #

Run the build runner to generate type-safe code:

flutter pub run build_runner build

This creates lib/gen/enviro.gen.dart with your environment configuration.

4. Use in Your App #

import 'package:your_app/gen/enviro.gen.dart';

void main() async {
  // Initialize with default environment (.env)
  await Enviro.initialize();
  
  // Or set a specific environment
  await Enviro.setEnvironment(EnviroEnvironment.DEVELOPMENT);
  
  // Access your environment variables with type safety
  final apiUrl = Enviro.apiUrl; // String
  final port = Enviro.port; // int
  final debug = Enviro.debug; // bool
  final logLevel = Enviro.logLevel; // String
  
  print('API URL: $apiUrl');
  print('Port: $port');
  print('Debug mode: $debug');
}

🎯 Advanced Usage #

Environment Switching #

// Switch to staging environment
await Enviro.setEnvironment(EnviroEnvironment.STAGING);

// Switch to production
await Enviro.setEnvironment(EnviroEnvironment.DEFAULT);

// Check current environment
final currentEnv = Enviro.currentEnvironment;
print('Current environment: $currentEnv');

Fallback Mechanism #

If a key is missing in the current environment, it automatically falls back to the DEFAULT (.env) environment:

// If API_URL is missing in .env-development, 
// it will use the value from .env
final apiUrl = Enviro.apiUrl;

Type Safety #

Enviro automatically detects types based on values across all environments:

// These are automatically typed based on your .env values
final apiUrl = Enviro.apiUrl;        // String
final port = Enviro.port;           // int  
final debug = Enviro.debug;         // bool
final timeout = Enviro.timeout;     // double

🔧 Configuration #

Build Configuration #

Add to your build.yaml (optional):

targets:
  $default:
    builders:
      enviro:
        options:
          # Custom options can be added here

Environment File Naming #

• .env → DEFAULT environment
• .env-development → DEVELOPMENT environment
• .env-staging → STAGING environment
• .env-production → PRODUCTION environment
• .env-custom-name → CUSTOM_NAME environment

🛠️ Development #

Running Build Runner #

# One-time build
flutter pub run build_runner build

# Watch mode (rebuilds on changes)
flutter pub run build_runner watch

# Clean and rebuild
flutter pub run build_runner build --delete-conflicting-outputs

Validation #

Enviro automatically validates:

• ✅ All .env files are included in pubspec.yaml assets
• ✅ At least one .env file exists
• ✅ .env file exists as the default environment
• ✅ Key consistency across environments

📝 Generated Code Example #

Here's what gets generated in lib/gen/enviro.gen.dart:

// GENERATED CODE - DO NOT MODIFY BY HAND
// Generated by enviro package

import 'dart:async';
import 'package:flutter/services.dart' show rootBundle;

/// Available environments
enum EnviroEnvironment {
  DEFAULT,
  DEVELOPMENT,
  STAGING,
}

/// Main class for accessing environment variables
class Enviro {
  Enviro._(); // Private constructor

  /// Set the current environment
  static Future<void> setEnvironment(EnviroEnvironment environment) async {
    _currentEnvironment = environment;
    _isInitialized = false;
    await _loadEnvironment();
  }

  /// Get API_URL from current environment
  static String get apiUrl => _getValue('API_URL');

  /// Get PORT from current environment  
  static int get port => int.parse(_getValue('PORT'));

  /// Get DEBUG from current environment
  static bool get debug => _getValue('DEBUG').toLowerCase() == 'true';

  // ... more getters for each environment variable
}

🚨 Troubleshooting #

Common Issues #

1. Missing .env files in pubspec.yaml

W [enviro] WARNING: Missing .env files in pubspec.yaml assets: .env-development, .env-staging

Solution: Add missing files to pubspec.yaml assets section.

2. No .env files found

[enviro] ERROR: No .env files found in project root

Solution: Create at least a .env file in your project root.

3. .env file not found

[enviro] ERROR: .env file not found in project root

Solution: Create a .env file as the default environment.

4. Key not found

Exception: Key "API_URL" not found in any environment

Solution: Add the missing key to your .env files.

Debug Mode #

Enable verbose logging by running build_runner with debug flag:

flutter pub run build_runner build --verbose

🤝 Contributing #

Contributions are welcome! Please feel free to submit a Pull Request.

Development Setup #

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

📄 License #

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments #

• Inspired by the need for type-safe environment configuration in Flutter
• Built with build_runner and build packages
• Thanks to the Dart and Flutter communities

Made with ❤️ for the Flutter community