A lightweight modular library for localization (l10n) functionality.

Goals

To enable localization which supports

• Localized file update without recompile,
• Easy and safe use through named method and argument generation,
• Small file size, treeshaking both unused locales and unused messages.

Status - experimental

• Serialize to binary: -
• Serialize to JSON: :heavy_check_mark:
• Deserialize JSON: :heavy_check_mark:
• Deserialize JSON using browser JS: -
• Deserialize binary: -
• Tree shake message files: -

Partitioning

The package is partitioned to allow a package to consume some parts of the library only as a dev_dependency, not including the message building and serialization packages in the dependencies for the application.

messages

Contains the interface for a MessageList and the different subtypes of Messages as well as the functionality to parse a data file into a MessageList.

messages_builder

The builder to generate the named methods and data files from the input arb translation files. Has a dependency on messages_serializer and messages.

messages_serializer

The logic for serializing arb message files into data files.

Example

Add package:messages and package:messages_builder to your dependencies:

dart pub add messages
dart pub add dev:messages_builder

Given translation message files in two languages: en.arb This reference file is written by the developer.

{
    "@@locale":"en",
    "@@context": "AboutPage",
    "aboutMessage": "About {website}",
    "@aboutMessage": {
        "placeholders": {
            "website" : {
                "type":"string"
            }
        }
    }
}

and fr.arb This translated file was created by a translator given the reference en.arb.

{
    "@@locale":"fr",
    "@@context": "AboutPage",
    "aboutMessage": "À propos de {website}",
}

you can then run

dart run build_runner build -d

This will generate both code to call your messages, as well as data files which will be shipped with your application. You can then use these generated files by importing the generated files:

import 'dart:io';

import 'package:example/aboutpage_arb_file.g.dart'; // <-- This was generated right now
import 'package:messages/messages_native.dart';
import 'package:messages/package_intl_object.dart';

void main() {
  final aboutPageMessages = AboutPageMessages(
    (String id) => File('lib/$id').readAsBytesSync(),
    OldIntlObject(),
  );
  aboutPageMessages.loadLocale('fr');
  print(aboutPageMessages.aboutMessage(website: 'mywebsite.com')); // 'À propos de mywebsite.com'
  aboutPageMessages.loadLocale('en');
  print(aboutPageMessages.aboutMessage(website: 'mywebsite.com')); // 'About mywebsite.com'
}

Optionally, add options to your pubspec.yaml by specifying any of these keys:

package_options:
  messages_builder:
    generateMethods: true # whether to generate named methods
    generateFindById: false # whether to allow messages to be retrieved by ID
    generateFindBy: integer # {none, integer, enumerate}, the type of key to use
    header: | # the custom header message. Will always be prefixed by // in the generated code.
      Generated by flutter_messages.

      // Some custom
      // multi
      // line
      // header