Awesome Open Source
Awesome Open Source

Easy and Fast internationalization for your Flutter Apps

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Why easy_localization?

  • 🚀 Easy translations for many languages
  • 🔌 Load translations as JSON, CSV, Yaml, Xml using Easy Localization Loader
  • 💾 React and persist to locale changes
  • ⚡ Supports plural, gender, nesting, RTL locales and more
  • ↩️ Fallback locale keys redirection
  • ⁉️ Error widget for missing translations
  • ❤️ Extension methods on Text and BuildContext
  • 💻 Code generation for localization files and keys.
  • 🛡️ Null safety
  • 🖨️ Customizable logger.

Getting Started

🔩 Installation

Add to your pubspec.yaml:

dependencies:
  easy_localization: <last_version>

Create folder and add translation files like this

assets
└── translations
    ├── {languageCode}.{ext}                  //only language code
    └── {languageCode}-{countryCode}.{ext}    //or full locale code

Example:

assets
└── translations
    ├── en.json
    └── en-US.json 

Declare your assets localization directory in pubspec.yaml:

flutter:
  assets:
    - assets/translations/

🔌 Loading translations from other resources

You can use JSON,CSV,HTTP,XML,Yaml files, etc.

See Easy Localization Loader for more info.

⚠️ Note on iOS

For translation to work on iOS you need to add supported locales to ios/Runner/Info.plist as described here.

Example:

<key>CFBundleLocalizations</key>
<array>
	<string>en</string>
	<string>nb</string>
</array>

⚙️ Configuration app

Add EasyLocalization widget like in example

import 'package:flutter/material.dart';
import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:easy_localization/easy_localization.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await EasyLocalization.ensureInitialized();
  
  runApp(
    EasyLocalization(
      supportedLocales: [Locale('en', 'US'), Locale('de', 'DE')],
      path: 'assets/translations', // <-- change the path of the translation files 
      fallbackLocale: Locale('en', 'US'),
      child: MyApp()
    ),
  );
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      localizationsDelegates: context.localizationDelegates,
      supportedLocales: context.supportedLocales,
      locale: context.locale,
      home: MyHomePage()
    );
  }
}

Full example

📜 Easy localization widget properties

Properties Required Default Description
key false Widget key.
child true Place for your main page widget.
supportedLocales true List of supported locales.
path true Path to your folder with localization files.
assetLoader false RootBundleAssetLoader() Class loader for localization files. You can use custom loaders from Easy Localization Loader or create your own class.
fallbackLocale false Returns the locale when the locale is not in the list supportedLocales.
startLocale false Overrides device locale.
saveLocale false true Save locale in device storage.
useFallbackTranslations false false If a localization key is not found in the locale file, try to use the fallbackLocale file.
useOnlyLangCode false false Trigger for using only language code for reading localization files.Example:en.json //useOnlyLangCode: trueen-US.json //useOnlyLangCode: false
errorWidget false FutureErrorWidget() Shows a custom error widget when an error occurs.

Usage

🔥 Initialize library

Call EasyLocalization.ensureInitialized() in your main before runApp.

void main() async{
  // ...
  // Needs to be called so that we can await for EasyLocalization.ensureInitialized();
  WidgetsFlutterBinding.ensureInitialized();

  await EasyLocalization.ensureInitialized();
  // ...
  runApp(....)
  // ...
}

🔥 Change or get locale

Easy localization uses extension methods [BuildContext] for access to locale.

It's more easiest way change locale or get parameters 😉.

ℹ️ No breaking changes, you can use old the static method EasyLocalization.of(context)

Example:

context.locale = Locale('en', 'US');

print(context.locale.toString());

🔥 Translate tr()

Main function for translate your language keys

You can use extension methods of [String] or [Text] widget, you can also use tr() as a static function.

Text('title').tr() //Text widget

print('title'.tr()); //String

var title = tr('title') //Static function

Arguments:

Name Type Description
args List<String> List of localized strings. Replaces {} left to right
namedArgs Map<String, String> Map of localized strings. Replaces the name keys {key_name} according to its name
gender String Gender switcher. Changes the localized string based on gender string

Example:

{
   "msg":"{} are written in the {} language",
   "msg_named":"Easy localization are written in the {lang} language",
   "msg_mixed":"{} are written in the {lang} language",
   "gender":{
      "male":"Hi man ;) {}",
      "female":"Hello girl :) {}",
      "other":"Hello {}"
   }
}
// args
Text('msg').tr(args: ['Easy localization', 'Dart']),

// namedArgs
Text('msg_named').tr(namedArgs: {'lang': 'Dart'}),

// args and namedArgs
Text('msg_mixed').tr(args: ['Easy localization'], namedArgs: {'lang': 'Dart'}),

// gender
Text('gender').tr(gender: _gender ? "female" : "male"),

🔥 Plurals plural()

You can translate with pluralization. To insert a number in the translated string, use {}. Number formatting supported, for more information read NumberFormat class documentation.

You can use extension methods of [String] or [Text] widget, you can also use plural() as a static function.

Arguments:

Name Type Description
value num Number value for pluralization
args List<String> List of localized strings. Replaces {} left to right
format NumberFormat Formats a numeric value using a NumberFormat class

Example:

{
  "day": {
    "zero":"{} дней",
    "one": "{} день",
    "two": "{} дня",
    "few": "{} дня",
    "many": "{} дней",
    "other": "{} дней"
  },
  "money": {
    "zero": "You not have money",
    "one": "You have {} dollar",
    "many": "You have {} dollars",
    "other": "You have {} dollars"
  },
  "money_args": {
    "zero": "{} has no money",
    "one": "{} has {} dollar",
    "many": "{} has {} dollars",
    "other": "{} has {} dollars"
  }
}

⚠️ Key "other" required!

//Text widget with format
Text('money').plural(1000000, format: NumberFormat.compact(locale: context.locale.toString())) // output: You have 1M dollars

//String
print('day'.plural(21)); // output: 21 день

//Static function
var money = plural('money', 10.23) // output: You have 10.23 dollars

//Static function with arguments
var money = plural('money_args', 10.23, args: ['John', '10.23'])  // output: John has 10.23 dollars

🔥 Linked translations:

If there's a translation key that will always have the same concrete text as another one you can just link to it. To link to another translation key, all you have to do is to prefix its contents with an @: sign followed by the full name of the translation key including the namespace you want to link to.

Example:

{
  ...
  "example": {
    "hello": "Hello",
    "world": "World!",
    "helloWorld": "@:example.hello @:example.world"
  }
  ...
}
print('example.helloWorld'.tr()); //Output: Hello World!

You can also do nested anonymous and named arguments inside the linked messages.

Example:

{
  ...
  "date": "{currentDate}.",
  "dateLogging": "INFO: the date today is @:date"
  ...
}
print('dateLogging'.tr(namedArguments: {'currentDate': DateTime.now().toIso8601String()})); //Output: INFO: the date today is 2020-11-27T16:40:42.657.

Formatting linked translations:

Formatting linked locale messages If the language distinguishes cases of character, you may need to control the case of the linked locale messages. Linked messages can be formatted with modifier @.modifier:key

The below modifiers are available currently.

  • upper: Uppercase all characters in the linked message.
  • lower: Lowercase all characters in the linked message.
  • capitalize: Capitalize the first character in the linked message.

Example:

{
  ...
  "example": {
    "fullName": "Full Name",
    "emptyNameError": "Please fill in your @.lower:example.fullName"
  }
  ...
}

⚠️ Key "other" required!

//Text widget with format
Text('money').plural(1000000, format: NumberFormat.compact(locale: context.locale.toString())) // output: You have 1M dollars

//String
print('day'.plural(21)); // output: 21 день

//Static function
var money = plural('money', 10.23) // output: You have 10.23 dollars

🔥 Delete save locale deleteSaveLocale()

Output:

print('example.emptyNameError'.tr()); //Output: Please fill in your full name

🔥 Reset locale resetLocale()

Reset locale to device locale

Example:

RaisedButton(
  onPressed: (){
    context.resetLocale();
  },
  child: Text(LocaleKeys.reset_locale).tr(),
)

🔥 Get device locale deviceLocale

Get device locale

Example:

print(${context.deviceLocale.toString()}) // OUTPUT: en_US

🔥 Delete save locale deleteSaveLocale()

Clears a saved locale from device storage

Example:

RaisedButton(
  onPressed: (){
    context.deleteSaveLocale();
  },
  child: Text(LocaleKeys.reset_locale).tr(),
)

🔥 Get Easy localization widget properties

At any time, you can take the main properties of the Easy localization widget using [BuildContext].

Are supported: supportedLocales, fallbackLocale, localizationDelegates.

Example:

print(context.supportedLocales); // output: [en_US, ar_DZ, de_DE, ru_RU]

print(context.fallbackLocale); // output: en_US

💻 Code generation

Code generation supports only json files, for more information run in terminal flutter pub run easy_localization:generate -h

Command line arguments

Arguments Short Default Description
--help -h Help info
--source-dir -S resources/langs Folder containing localization files
--source-file -s First file File to use for localization
--output-dir -O lib/generated Output folder stores for the generated file
--output-file -o codegen_loader.g.dart Output file name
--format -f json Support json or keys formats

🔌 Localization asset loader class

Steps:

  1. Open your terminal in the folder's path containing your project
  2. Run in terminal flutter pub run easy_localization:generate
  3. Change asset loader and past import.
import 'generated/codegen_loader.g.dart';
...
void main(){
  runApp(EasyLocalization(
    child: MyApp(),
    supportedLocales: [Locale('en', 'US'), Locale('ar', 'DZ')],
    path: 'resources/langs',
    assetLoader: CodegenLoader()
  ));
}
...
  1. All done!

🔑 Localization keys

If you have many localization keys and are confused, key generation will help you. The code editor will automatically prompt keys

Steps:

  1. Open your terminal in the folder's path containing your project
  2. Run in terminal flutter pub run easy_localization:generate -f keys -o locale_keys.g.dart
  3. Past import.
import 'generated/locale_keys.g.dart';
  1. All done!

How to usage generated keys:

print(LocaleKeys.title.tr()); //String
//or
Text(LocaleKeys.title).tr(); //Widget
  1. All done!

🖨️ Logger

[Easy Localization] logger based on [Easy Logger]

You can customize logger for you project

Show only lost keys message

Lost translations keys logged like warning messages. Change [Easy Logger] level for display only errors and warnings.

EasyLocalization.logger.enableLevels = [LevelMessages.error, LevelMessages.warning];

Logger off

For disable logger, change Build Modes in [Easy Logger] to empty List;

EasyLocalization.logger.enableBuildModes = [];

Catching logger messages

For catching logger messages you need override default printer function.

EasyLogPrinter customLogPrinter = (
  Object object, {
  String name,
  StackTrace stackTrace,
  LevelMessages level,
}) {
  ///Your function
  print('$name: ${object.toString()}');
};

/// override printer to custom
EasyLocalization.logger.printer = customLogPrinter;

Read more about Easy Logger

➕ Extensions helpers

String to locale

'en_US'.toLocale(); // Locale('en', 'US')

//with custom separator
'en|US'.toLocale(separator: '|') // Locale('en', 'US')

Locale to String with separator

Locale('en', 'US').toStringWithSeparator(separator: '|') // en|US

Screenshots

Arabic RTL English LTR Error widget
Arabic RTL English LTR Error widget

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