localization

Localization

Package to simplify in-app translation.

Install

Use the Localization package together with flutter_localization.

Add in your pubspec:

dependencies:
  flutter_localizations: 
    sdk: flutter
  localization: <last-version>

flutter:

  # json files directory
  assets:
    - lib/i18n/

Now, add the delegate in MaterialApp or CupertinoApp and define a path where the translation json files will be:

 @override
  Widget build(BuildContext context) {
    // set json file directory
    // default value is ['lib/i18n']
    LocalJsonLocalization.delegate.directories = ['lib/i18n'];
    
    //or set a map of translations
    MapLocalization.delegate.translations = {
      Locale('en', 'US'): {
        'welcome-text': 'This text is in english',
      },
      Locale('es', 'ES'): {
        'welcome-text': 'Este texto esta en español',
      },
      Locale('pt', 'BR'): {
        'welcome-text': 'Este texto está em português',
      },
    };

    return MaterialApp(
      localizationsDelegates: [
        // delegate from flutter_localization
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
        GlobalCupertinoLocalizations.delegate,
        
        // delegate from localization package.
        //json-file
        LocalJsonLocalization.delegate,
        //or map
        MapLocalization.delegate,
      ],
      home: HomePage(),
    );
  }

Json files

The json file pattern must have the name of the locale and its content must be a json of key and value ONLY. Create the files in the directory configured (LocalJsonLocalization.delegate.directories):

lib/i18n/en_US.json
lib/i18n/es_ES.json
lib/i18n/pt_BR.json

See an example of a translation json file:

en_US.json

{
  "welcome-text": "This text is in english"
}

es_ES.json

{
  "welcome-text": "Este texto esta en español"
}

pt_BR.json

{
  "welcome-text": "Este texto está em português"
}

Using

For convenience, the i18n() method has been added to the String class via extension. So just add the translation json file key as string and use i18n() method to bring up the translation.

String text = 'welcome-text'.i18n();
print(text) // prints 'This text is in english'

We can also work with arguments for translation. Use %s notion:

{
  "welcome-text": "Welcome, %s"
}

String text = 'welcome-text'.i18n(['Peter']);
print(text); // Welcome, Peter

The %s notation can also be retrieved positionally. Just use %s0, %s1, %s2...

You could plularization your Strings. Use %b{true:false} notion, where left is a string value when condition is true and on the right is a value when condition is false:

{
  "person-text": "Welcome, %b{people:person}"
}

final count = 2;
String text = 'person-text'.i18n(
        [], //args is a required positional parameter, if you don't gave a %s notation give a empty list []
        conditions: [count > 1]);
print(text); // Welcome, people

THAT`S IT!

Additional settings

After installation, the Localization package is fully integrated into Flutter and can reflect changes made natively by the SDK. Here are some examples of configurations that we will be able to do directly in MaterialApp or CupertinoApp.

Add supported languages

This setting is important to tell Flutter which languages your app is prepared to work with. We can do this by simply adding the Locale in the supportedLocales property:

return MaterialApp(
  supportedLocales: [
    Locale('en', 'US'),
    Locale('es', 'ES'),
    Locale('pt', 'BR'),
  ],
  ...
);

Locale resolution

Often we will not have to make some decisions about what to do when the device language is not supported by our app or work with a different translation for different countries (eg pt_BR(Brazil) and pt_PT(Portugal). For these and other decisions we can use the dsdsk property to create a resolution strategy:

return MaterialApp(
  localeResolutionCallback: (locale, supportedLocales) {
      if (supportedLocales.contains(locale)) {
        return locale;
      }

      // define pt_BR as default when de language code is 'pt'
      if (locale?.languageCode == 'pt') {
        return Locale('pt', 'BR');
      }

      // default language
      return Locale('en', 'US');
  },
  ...
);

Localization UI

Web version | Download now

We have an application to help you configure your translation keys. The project is also open-source, so be fine if you want to help it evolve!

Features and bugs

Localization package is constantly growing. Let us know what you think of all this. If you agree, give a Star in that repository representing that you are signing and consenting to the proposed standard.

Questions and Problems

The issues channel is open for questions, to report problems and suggestions, do not hesitate to use this communication channel.

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