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:

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

Next Steps After Generation #

Add additional language ARB files:

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

Run Flutter's localization generator:
```
flutter gen-l10n
```

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:

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

Happy Localizing! 🌍

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