Rosetta

Rosetta is a Rails engine proviving a full-fledged internationalization (i18n) solution for your Rails application. It is designed with the following principles in mind:

• Unobtrusiveness: i18n matters should not get in your way developing application code.
• Maintanbility: time should not be spent editing, organizing or deduplicating translation files.
• Separation of concerns: development work is separated from translation work.

Rosetta answers those design principles by offering the following features:

• Texts as translation keys: Inspired by the gettext approach, Rosetta uses the texts themselves as translation keys. The language the codebase is written into is the default locale.
• Key autodiscovery: New translation keys are automatically discovered and uniquely saved to the database. No more time spent between views and yaml files.
• A dedicated interface: Translators can work on a dedicated interface, separated from the codebase. They can search, filter, edit and create translations in a user-friendly environment

A real-life example speaking louder than words, here is a comparison between the Rails default I18n approach and Rosetta:

<!-- Rails with I18n -->
<h1 class="text-2xl font-semibold"><%= t("pages.home.greetings") %> </h1>
<p class="text-xl font-medium"><%= t("pages.home.introductory_text") %></p>

<!-- Rails with Rosetta -->
<h1 class="text-2xl font-semibold"><%= _ "Hi! Welcome to Rosetta" %> </h1>
<p class="text-xl font-medium">
  <%= _ "Rosetta is a Rails engine proviving a full-fledged internationalization (i18n) solution for your Rails application." %>
</p>

Roadmap

Warning

Rosetta is still early in its development, and is subject to breaking changes even on minor version updates. Please refer to the releases section for more information.

Feature	tracking	released
Base translations		0.1.1
Pluralization API	#5
Context API	#6
Interpolation API	#8

Installation

Add this line to your application's Gemfile:

gem "rosetta-rails"

And then execute:

$ bundle install

Run the following command to install the required migrations:

$ rails rosetta:install:migrations
$ rails db:migrate

Finally, mount the engine in your config/routes.rb file:

Rails.application.routes.draw do
  mount Rosetta::Engine => "/rosetta"
end

And that's it! Run your server and visit http://localhost:3000/rosetta to check everything is running properly.

Usage

The Default locale

Note

By convention in Rosetta, the default locale should be the locale your codebase is written into. This, in theory should not change once it is set.

The first time you visit the Rosetta interface, you will be prompted to set the default locale:

Enter the name and the code for the locale your codebase is written into (probably English and en in most cases) and submit the form. You will be redirected to the rosetta homepage where your default locale will appear.

Adding a locale

Developers shout not worry about managing locales. Locales can be added through the Rosetta interface. Visit the interface and click on the "Add locale" button. You will be prompted to enter the name and code of the locale. Once added, the locale will immediately be available and ready to be translated.

Selecting the locale in the application

The current locale is globally available in the current thread the application is running in. You can access it through the Rosetta.locale method. This will return a Rosetta::Locale instance.

It is recommended to follow the Rails guides best practices to manage the locale across requests. Rosetta offers a similar helper method to set the locale for the current request:

class ApplicationController < ActionController::Base
  around_action :set_locale

  private

  def set_locale(&action)
    Rosetta.with_locale(params[:locale], &action)
  end

Where locale is the code of the locale you want to set. You can then set the locale by passing the locale code as a query parameter in the URL, like http://localhost:3000?locale=fr. If no locale exists for this code, the default locale is used instead.

You can access available locales through Rosetta.available_locales to build a selector your users can use to swith between locales:

<ul>
  <% Rosetta.available_locales.each do |locale| %>
    <li><%= link_to locale.name, root_path(locale: locale.code) %></li>
  <% end %>
</ul>

Translating your views

Important

Make sure you've correctly installed rosetta, and that your production environment has run the rosetta migrations properly before invoking the _ helper in your views.

As stated above, Rosetta is built with unobstrusiveness in mind. To translate your view, no need to come up with a translation key, figure out the file and appropriate nesting to write to. All you need to do is include the Rosetta::TranslationHelper in your ApplicationHelper and wrap your text with the _ method in your view:

module ApplicationHelper
  include Rosetta::TranslationHelper
end

<h1"><%= _ "Hi! Welcome to Rosetta" %> </h1>

Rosetta will automatically detect the new translation keys and save them to the database. You can then visit the Rosetta interface to add a translation for a given locale.

Adding translations

Translations can be added through the Rosetta interface. Visit the interface and click on "Manage" button next to the locale you want to add translations for. You will access the list of your app keys, and the corresponding translations, should they exist. To add or edit a translation, hover the translation cell and click on "edit". You can then enter the translation and save it.

Saving the new translation will not immediately reflect in your application. This is by desgin for performance reasons. To make new translations available in your app, click on the "deploy" button at the top of the page. Translations for the given locale will be reloaded and made available in your app.

Configuration

Configuring a base controller

By default, Rosetta inherits from ActionController::Base. If you want to restrict access to the Rosetta interface, you can make Rosetta inherit from your own base controller, by configuring it in the initializer:

# config/initializers/rosetta.rb

Rosetta.configure do |config|
  config.parent_controller_class = "AdminController"
end

Note: The class name needs to be a string.

Setting up the queue for the Autodiscovery Job

Rosetta uses a background job to automatically discover new translations in your codebase. It enqueues jobs in the queue set by default. To configure it to target another queue:

# config/initializers/rosetta.rb

Rosetta.configure do |config|
  config.queues[:autodiscovery] = "low_priority"
end

I18n Support

As of now, Rosetta does not integrate with the i18n gem as a custom backend. It might be done in the future, however it's been decided to build Rosetta independently for now. You still need to use i18n for backwards compatibility of your existing translations, localization, as well as the translations of gems that depend on it.

License

The gem is available as open source under the terms of the MIT License.