string_extractor_intl

Flutter String Extractor for Localization

🌍 A powerful command-line tool that automatically extracts hardcoded strings from your Flutter project and generates ARB files for internationalization (i18n) and localization (l10n).

Features

• 🔍 Automatically scans your Flutter project for hardcoded strings
• 📝 Generates ARB files with extracted strings
• 📝 Avoid Duplicates when extracting
• 🔄 Replaces hardcoded strings with localization calls (optional)
• 🛠️ Auto-configures MaterialApp with localization delegates
• 📋 Detects string variables and creates parameterized localizations
• ⚙️ Generates l10n.yaml configuration file
• 🔍 Dependency checking ensures required packages are installed
• 🎯 Smart filtering ignores URLs, asset paths, and other non-localizable strings

Installation

Add this package as a dev dependency in your pubspec.yaml:

dev_dependencies:
  string_extractor_intl: ^1.0.3

Then run:

flutter pub get

Prerequisites

Your Flutter project must have these dependencies in pubspec.yaml:

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter
  intl: ^0.19.0

The following section is specific to Flutter packages. for future generation
flutter:
uses-material-design: true
generate: true

Usage

Basic Usage (Extract Only)

Extract strings and generate ARB files without modifying your source code:

dart pub run string_extractor_intl:extract_strings

Advanced Usage

Extract and replace in files:

dart pub run string_extractor_intl:extract_strings --replace

Custom configuration:

dart pub run string_extractor_intl:extract_strings \
  --input lib/presentation \
  --output assets/l10n \
  --template-arb strings_en.arb \
  --class-name MyLocalizations \
  --replace

Show help:

dart pub run string_extractor_intl:extract_strings --help

Command Line Options

Option	Short	Default	Description
--input	-i	lib/presentation	Input directory to scan
--output	-o	lib/l10n	Output directory for localization files
--template-arb		app_en.arb	Template ARB file name
--class-name	-c	AppLocalizations	Name of the localization class
--replace	-r	false	Replace hardcoded strings with localization calls
--check-deps		true	Check for required dependencies
--help	-h		Show usage information

⚠️ Suggestion: run the extraction on the Presentation folder only to avoid taking unnecessary strings with:

dart pub run string_extractor_intl:extract_strings \ --input lib/presentation \

⚠️ CAUTION: Before Running with --replace Flag

READ THIS CAREFULLY BEFORE USING THE --replace OPTION:

🚨 MANDATORY BACKUP

• ALWAYS create a backup of your project before running with --replace
• Commit your changes to Git or copy your entire project folder
• The tool will modify multiple files in your project automatically
• There is no undo feature - you'll need your backup to revert changes

📖 READ INSTRUCTIONS THOROUGHLY

• Read this entire README before using the replacement feature
• Test the tool on a small project first to understand how it works
• Review the generated code after replacement to ensure it meets your needs

🔧 POST-REPLACEMENT REQUIREMENTS

After running with --replace, you MUST run these commands:

# Install/update dependencies
flutter pub get

# Generate localization files
flutter gen-l10n

⚠️ IMPORTANT WARNINGS before using --replace

• Review all changes before committing to version control
• Test your app thoroughly after replacement
• Some strings may need manual adjustment after automatic replacement
• Variables in strings will be converted to parameterized localizations
• MaterialApp will be automatically configured with localization delegates

How It Works

1. String Detection

The tool scans your Dart files and identifies hardcoded strings, excluding:

• Import/export statements
• Asset paths and URLs
• File extensions
• Widget class names
• Single characters and numbers

2. Variable Detection

Automatically detects variables in strings:

• "Hello $_name" → S.of(context).hello('$_name')
• "Count: ${count}" → S.of(context).count('$count')

3. ARB File Generation

Creates structured ARB files with:

• Proper locale annotations
• Parameter definitions for variables
• Descriptive comments
• Sorted keys for consistency

4. Code Replacement (Optional)

When using --replace:

• Replaces hardcoded strings with localization calls
• Adds necessary import statements
• Configures MaterialApp with localization delegates
• Preserves variable references in parameterized strings

Example

Before

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'My App',
      home: Scaffold(
        appBar: AppBar(title: Text('Welcome')),
        body: Text('Hello $_username!'),
      ),
    );
  }
}

After (with --replace)

import 'l10n/generated/app_localizations.dart';

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      localizationsDelegates: S.localizationsDelegates,
      supportedLocales: S.supportedLocales,
      title: S.of(context).myApp,
      home: Scaffold(
        appBar: AppBar(title: Text(S.of(context).welcome)),
        body: Text(S.of(context).hello('$_username')),
      ),
    );
  }
}

Generated ARB File (app_en.arb)

{
  "@@locale": "en",
  "hello": "Hello {username}!",
  "@hello": {
    "description": "Localized string with parameters: username",
    "placeholders": {
      "username": {
        "type": "String",
        "example": "John"
      }
    }
  },
  "myApp": "My App",
  "@myApp": {
    "description": "Localized string"
  },
  "welcome": "Welcome",
  "@welcome": {
    "description": "Localized string"
  }
}

Generated Files

The tool creates several files:

1. ARB File (lib/l10n/app_en.arb) - Contains extracted strings
2. l10n.yaml - Configuration for Flutter's localization generator
3. Modified Dart files - Updated with localization calls (if using --replace)

Next Steps After Generation

1. Add additional language ARB files:

   lib/l10n/app_es.arb  (Spanish)
   lib/l10n/app_fr.arb  (French)
   lib/l10n/app_de.arb  (German)
   

2. Run Flutter's localization generator:

   flutter gen-l10n
   

3. Import and use in your app:

   import 'l10n/generated/app_localizations.dart';
   
   // In your MaterialApp
   MaterialApp(
     localizationsDelegates: S.localizationsDelegates,
     supportedLocales: S.supportedLocales,
     // ...
   )
   

For more details, read this article.

Troubleshooting

Common Issues

"pubspec.yaml not found"

• Ensure you're running the command from your Flutter project root

"Missing required dependencies"

• Add intl and flutter_localizations to your pubspec.yaml
• Run flutter pub get

Generated strings not accessible

• Run flutter gen-l10n after generating ARB files
• Check that l10n.yaml exists in your project root

Compilation errors after replacement

• Ensure you ran flutter pub get and flutter gen-l10n
• Check that imports were added correctly
• Review replaced strings for accuracy

Best Practices

• Start with extraction only (without --replace) to review strings
• Test on a copy of your project first
• Review generated ARB files before adding translations
• Use meaningful string content for better key generation
• Keep backups when using the replacement feature

Contributing

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

License

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

Support

If you encounter any issues or have questions:

1. Check the troubleshooting section above
2. Search existing issues on GitHub
3. Create a new issue with detailed information about your problem

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Happy Localizing! 🌍