Translations code generator

This is a simple tool to generate the translations code for the Dart/Flutter projects.

Quickstart • Pub.dev

Install

1. Add the dependency

dependencies:
  translations_code_gen: ^1.3.4

2. Run this commend

flutter pub get

Usage

1. Create a translations files in assets folder

Create a folder called assets in the root of your project and create a file called en.json and ar.json and add the following content:

example: assets/translations/en.json

{
  "GENERAL": {
    "HELLO": "Hello",
    "WELCOME": "Welcome",
    "WELCOME_USER": "Welcome {name}!",
    "GREETING_WITH_TIME": "Good {timeOfDay}, {name}!"
  },
  "HOME": {
    "TITLE": "Home"
  },
  "MESSAGES": {
    "SIMPLE_MESSAGE": "This is a simple message",
    "USER_PROFILE": "User {username} has {count} notifications",
    "POSITIONAL_EXAMPLE": "First: {}, Second: {}, Third: {}",
    "MIXED_PLACEHOLDERS": "Hello {name}, you have {} new messages and {} pending tasks"
  }
}

example: assets/translations/ar.json

{
  "GENERAL": {
    "HELLO": "مرحبا",
    "WELCOME": "أهلا بك",
    "WELCOME_USER": "أهلا بك {name}!",
    "GREETING_WITH_TIME": "{timeOfDay} طيب، {name}!"
  },
  "HOME": {
    "TITLE": "الرئيسية"
  },
  "MESSAGES": {
    "SIMPLE_MESSAGE": "هذه رسالة بسيطة",
    "USER_PROFILE": "المستخدم {username} لديه {count} إشعارات",
    "POSITIONAL_EXAMPLE": "الأول: {}، الثاني: {}، الثالث: {}",
    "MIXED_PLACEHOLDERS": "مرحبا {name}، لديك {} رسائل جديدة و {} مهام معلقة"
  }
}

2. Add the translations file paths to the pubspec.yaml or translations_code_gen.yaml file

translations_code_gen:
  keys:
    input: 'assets/translations/en.json'
    output: 'lib/translations/keys.dart'
  values:
    input: 'assets/translations/'
    output: 'lib/translations/values/'

Run this command to generate the translations keys and values to the output:

flutter pub run translations_code_gen

The -g or --generate flag is optional, if you don't use it, the tool will normally generate dart keys and values code for you.

This will generate the following keys to the lib/translations/keys.dart file:

// GENERATED CODE - DO NOT MODIFY BY HAND
// ignore_for_file: constant_identifier_names, camel_case_types

import 'package:easy_localization/easy_localization.dart';

class GENERAL {
  static const String HELLO = "GENERAL.HELLO";
  static String hello() => HELLO.tr();
  static const String WELCOME = "GENERAL.WELCOME";
  static String welcome() => WELCOME.tr();
  static const String WELCOME_USER = "GENERAL.WELCOME_USER";
  static String welcomeUser({String? name, }) => WELCOME_USER.tr(namedArgs: {if (name != null) 'name': name, });
  static const String GREETING_WITH_TIME = "GENERAL.GREETING_WITH_TIME";
  static String greetingWithTime({String? timeOfDay, String? name, }) => GREETING_WITH_TIME.tr(namedArgs: {if (timeOfDay != null) 'timeOfDay': timeOfDay, if (name != null) 'name': name, });
}

class HOME {
  static const String TITLE = "HOME.TITLE";
  static String title() => TITLE.tr();
}

class MESSAGES {
  static const String SIMPLE_MESSAGE = "MESSAGES.SIMPLE_MESSAGE";
  static String simpleMessage() => SIMPLE_MESSAGE.tr();
  static const String USER_PROFILE = "MESSAGES.USER_PROFILE";
  static String userProfile({String? username, String? count, }) => USER_PROFILE.tr(namedArgs: {if (username != null) 'username': username, if (count != null) 'count': count, });
  static const String POSITIONAL_EXAMPLE = "MESSAGES.POSITIONAL_EXAMPLE";
  static String positionalExample({List<String?>? args, }) => POSITIONAL_EXAMPLE.tr(args: args?.whereType<String>().toList(), );
  static const String MIXED_PLACEHOLDERS = "MESSAGES.MIXED_PLACEHOLDERS";
  static String mixedPlaceholders({String? name, List<String?>? args, }) => MIXED_PLACEHOLDERS.tr(args: args?.whereType<String>().toList(), namedArgs: {if (name != null) 'name': name, });
}

and the following values to the en.dart and ar.dart file to lib/translations/values/

example: lib/translations/values/en.dart

// GENERATED CODE - DO NOT MODIFY BY HAND
// ignore_for_file: constant_identifier_names

import '../keys.dart'; // sometimes you need to change this path to match your project structure

const Map<String, String> _general  = {
  GENERAL.HELLO: "Hello",
  GENERAL.WELCOME: "Welcome",
  GENERAL.WELCOME_USER: "Welcome {name}!",
  GENERAL.GREETING_WITH_TIME: "Good {timeOfDay}, {name}!",
};

const Map<String, String> _home  = {
  HOME.TITLE: "Home",
};

const Map<String, String> _messages  = {
  MESSAGES.SIMPLE_MESSAGE: "This is a simple message",
  MESSAGES.USER_PROFILE: "User {username} has {count} notifications",
  MESSAGES.POSITIONAL_EXAMPLE: "First: {}, Second: {}, Third: {}",
  MESSAGES.MIXED_PLACEHOLDERS: "Hello {name}, you have {} new messages and {} pending tasks",
};

final Map<String, String> enValues = {
  ..._general,
  ..._home,
  ..._messages,
};

example: lib/translations/values/ar.dart

// GENERATED CODE - DO NOT MODIFY BY HAND
// ignore_for_file: constant_identifier_names

import '../keys.dart'; // sometimes you need to change this path to match your project structure

const Map<String, String> _general  = {
  GENERAL.HELLO: "مرحبا",
  GENERAL.WELCOME: "أهلا بك",
  GENERAL.WELCOME_USER: "أهلا بك {name}!",
  GENERAL.GREETING_WITH_TIME: "{timeOfDay} طيب، {name}!",
};

const Map<String, String> _home  = {
  HOME.TITLE: "الرئيسية",
};

const Map<String, String> _messages  = {
  MESSAGES.SIMPLE_MESSAGE: "هذه رسالة بسيطة",
  MESSAGES.USER_PROFILE: "المستخدم {username} لديه {count} إشعارات",
  MESSAGES.POSITIONAL_EXAMPLE: "الأول: {}، الثاني: {}، الثالث: {}",
  MESSAGES.MIXED_PLACEHOLDERS: "مرحبا {name}، لديك {} رسائل جديدة و {} مهام معلقة",
};

final Map<String, String> arValues = {
  ..._general,
  ..._home,
  ..._messages,
};

You might have to change the keys import path to match your project structure.

Placeholder Types and Usage

This package supports three types of placeholders in your translation strings:

1. Named Placeholders {name}

Named placeholders use curly braces with a parameter name inside. They generate methods with named parameters.

Translation JSON:

{
  "WELCOME_USER": "Welcome {name}!",
  "USER_STATS": "User {username} has {count} points"
}

Generated Dart Code:

static String welcomeUser({String? name, }) => _WELCOME_USER.tr(namedArgs: {if (name != null) 'name': name, });
static String userStats({String? username, String? count, }) => _USER_STATS.tr(namedArgs: {if (username != null) 'username': username, if (count != null) 'count': count, });

Usage:

Text(GENERAL.welcomeUser(name: 'John'))
Text(GENERAL.userStats(username: 'Alice', count: '150'))

2. Positional Placeholders {}

Positional placeholders use empty curly braces {}. They generate methods that accept a list of arguments.

Translation JSON:

{
  "ORDERED_LIST": "First: {}, Second: {}, Third: {}"
}

Generated Dart Code:

static String orderedList({List<String?>? args, }) => _ORDERED_LIST.tr(args: args?.whereType<String>().toList(), );

Usage:

Text(MESSAGES.orderedList(args: ['Apple', 'Banana', 'Cherry']))

3. Mixed Placeholders {name} + {}

You can combine both named and positional placeholders in the same translation string.

Translation JSON:

{
  "MIXED_MESSAGE": "Hello {name}, you have {} new messages and {} pending tasks"
}

Generated Dart Code:

static String mixedMessage({String? name, List<String?>? args, }) => _MIXED_MESSAGE.tr(args: args?.whereType<String>().toList(), namedArgs: {if (name != null) 'name': name, });

Usage:

Text(MESSAGES.mixedMessage(
  name: 'Alice',
  args: ['5', '3']
))

4. Simple Strings (No Placeholders)

Strings without placeholders generate simple methods that call .tr() directly.

Translation JSON:

{
  "SIMPLE_MESSAGE": "This is a simple message"
}

Generated Dart Code:

static String simpleMessage() => _SIMPLE_MESSAGE.tr();

Usage:

Text(MESSAGES.simpleMessage())

Key Features

• Type Safety: All generated methods provide compile-time type checking
• Null Safety: All parameters are nullable with proper null checks
• easy_localization Integration: Generated code works seamlessly with the easy_localization package
• Automatic Formatting: Translation keys are converted to camelCase method names
• Public Constants: Translation key constants are publicly accessible for direct usage and testing
• Flexible Access: Use either the generated methods or access the constants directly

4. Use the generated code

import 'package:flutter/material.dart';

import './translations/keys.dart';

// any translation package

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(HOME.title()),
      ),
      body: Column(
        children: [
          // Simple translation without placeholders
          Text(GENERAL.hello()),
          
          // Named placeholder example
          Text(GENERAL.welcomeUser(name: 'John')),
          
          // Multiple named placeholders
          Text(GENERAL.greetingWithTime(
            timeOfDay: 'morning', 
            name: 'Sarah'
          )),
          
          // Positional placeholders
          Text(MESSAGES.positionalExample(
            args: ['Apple', 'Banana', 'Cherry']
          )),
          
          // Mixed placeholders (named + positional)
          Text(MESSAGES.mixedPlaceholders(
            name: 'Alice',
            args: ['5', '3']
          )),
          
          // User profile with named placeholders
          Text(MESSAGES.userProfile(
            username: 'developer',
            count: '12'
          )),
        ],
      ),
    );
  }
}

5. Public Constant Accessibility

Starting from version 1.3.6, all translation key constants are publicly accessible, allowing for more flexible usage patterns:

Direct Constant Access

You can now access the translation key constants directly:

// Access constants directly for custom usage
String keyValue = GENERAL.HELLO; // "GENERAL.HELLO"
String translatedText = keyValue.tr(); // "Hello"

// Use in custom translation logic
Map<String, String> customTranslations = {
  GENERAL.HELLO: "Custom Hello",
  HOME.TITLE: "Custom Title",
};

// Useful for testing and debugging
print('Translation key: ${MESSAGES.USER_PROFILE}');

Benefits of Public Constants

• Testing: Easily test translation keys in unit tests
• Custom Logic: Build custom translation logic around the constants
• Debugging: Access raw translation keys for debugging purposes
• Integration: Better integration with other localization tools
• Flexibility: Choose between method calls or direct constant access

Usage Patterns

// Method approach (recommended for most cases)
Text(GENERAL.hello())

// Direct constant approach (for custom logic)
Text(GENERAL.HELLO.tr())

// Both approaches are equivalent and produce the same result

6. Same as above but with the --generate flag

flutter pub run translations_code_gen --generate=json-values

There are 4 types of code generation mode:

• dart (default): generate dart keys and values code
• dart-keys: generate dart keys only.
• dart-values: generate dart values only.
• json-values: generate json values only.

Output with the --generate=json-values flag

example: lib/translations/values/en.json

{
  "GENERAL.HELLO": "Hello",
  "GENERAL.WELCOME": "Welcome",
  "GENERAL.WELCOME_USER": "Welcome {name}!",
  "GENERAL.GREETING_WITH_TIME": "Good {timeOfDay}, {name}!",
  "HOME.TITLE": "Home",
  "MESSAGES.SIMPLE_MESSAGE": "This is a simple message",
  "MESSAGES.USER_PROFILE": "User {username} has {count} notifications",
  "MESSAGES.POSITIONAL_EXAMPLE": "First: {}, Second: {}, Third: {}",
  "MESSAGES.MIXED_PLACEHOLDERS": "Hello {name}, you have {} new messages and {} pending tasks"
}

example: lib/translations/values/ar.json

{
  "GENERAL.HELLO": "مرحبا",
  "GENERAL.WELCOME": "أهلا بك",
  "GENERAL.WELCOME_USER": "أهلا بك {name}!",
  "GENERAL.GREETING_WITH_TIME": "{timeOfDay} طيب، {name}!",
  "HOME.TITLE": "الرئيسية",
  "MESSAGES.SIMPLE_MESSAGE": "هذه رسالة بسيطة",
  "MESSAGES.USER_PROFILE": "المستخدم {username} لديه {count} إشعارات",
  "MESSAGES.POSITIONAL_EXAMPLE": "الأول: {}، الثاني: {}، الثالث: {}",
  "MESSAGES.MIXED_PLACEHOLDERS": "مرحبا {name}، لديك {} رسائل جديدة و {} مهام معلقة"
}

Development

Requirements

• Dart SDK: >=3.1.0 <4.0.0 (recommended: 3.9.2 or later)
• Flutter SDK: 3.35.4 or later (when using FVM)

Setting up with FVM (Flutter Version Manager)

This project uses FVM for Flutter and Dart SDK version management to ensure consistent development environments.

1. Install FVM

# Using Homebrew (macOS)
brew tap leoafarias/fvm
brew install fvm

# Using pub global
dart pub global activate fvm

# Using Chocolatey (Windows)
choco install fvm

2. Install and use the project's Flutter version

# Install the required Flutter version
fvm install 3.35.4

# Use it for this project
fvm use 3.35.4

3. Run commands with FVM

# Get dependencies
fvm dart pub get

# Run the application
fvm dart run bin/translations_code_gen.dart

# Analyze code
fvm dart analyze

# Run tests
fvm dart test

Without FVM

If you prefer not to use FVM, ensure you have Dart SDK 3.9.2 or later installed:

# Check your Dart version
dart --version

# Run the application
dart run bin/translations_code_gen.dart

Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Install dependencies with fvm dart pub get (or dart pub get)
4. Make your changes
5. Run tests and ensure code analysis passes
6. Commit your changes (git commit -m 'Add some amazing feature')
7. Push to the branch (git push origin feature/amazing-feature)
8. Open a Pull Request