Over-The-Air updates for Flutter Framework localizations.

Features:

  • using l10n strings in standard way as described in the Internationalizing Flutter apps tutorial.
  • fetch updated ARB files from your backend by defining just one class OtaService with two methods.
  • caching of the ARB files in the app's documents directory.
  • versioning of the ARB files to prevent unnecessary downloads. (e.g. if local version is newer than the remote one, the download is skipped at all)

Usage

1. l10n.yaml

Set synthetic-package to false in l10n.yaml. Example:

arb-dir: lib/l10n/arb
template-arb-file: app_en.arb
output-localization-file: l10n.dart
output-class: L10n

synthetic-package: false
output-dir: lib/l10n/generated

no-nullable-getter: true

More

2. Versioning

Define key fl_ota_version in ARB files. It is just number, which is increased at every change of the ARB files.

{
  "fl_ota_version": "1"
}

3. Generating files

  1. flutter gen-l10n - Generate standard stubs.
  2. dart run flutter_localizations_ota:generate - Generate stub for Over-The-Air

4. Define OtaService

In a real scenario, some backend API needs to be used.

import 'dart:convert';

import 'package:flutter_localizations_ota/flutter_localizations_ota.dart';

const root = 'https://justprodev.com/partners/flutter_localizations_ota/arb';

class ExampleOtaService implements OtaService {
  const ExampleOtaService();

  @override
  Future<int> getArbVersion(String localeName) async {
    final r = await http.get(Uri.parse('$root/app_$localeName.version'));
    return int.parse(r.body);
  }

  @override
  Future<String> getArbContent(String localeName) async {
    final r = await http.get(Uri.parse('$root/app_$localeName.arb'));
    return utf8.decode(r.bodyBytes);
  }
}

5. Setup App for Over-The-Air updates

import 'l10n/example_ota_service.dart';
import 'l10n/generated/l10n_remote.dart';

    return FlutterLocalizationsOta(
      otaService: const ExampleOtaService(),
      child: MaterialApp(
        theme: ThemeData(
          colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
          useMaterial3: true,
        ),
        home: MyHomePage(),
        localizationsDelegates: L10nRemote.localizationsDelegates,
        supportedLocales: L10nRemote.supportedLocales,
        locale: currentLocale,
      ),
      onError: (request, error, trace) {
        debugPrint(error.toString());
      },
    );
  }

6. Access translation anywhere in the app

import 'l10n/generated/l10n.dart';

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    final L = L10n.of(context)!;

    return Text(L.helloWorld);
  }
}

Find example for more info

Libraries

flutter_localizations_ota