Rails Engines are supported by Ruby-GetText-Package since 1.8.0. It's similar with supporting Rails. So you can understand this HOWTO well if you learn Rails localization with GetText before.

Read Ruby-GetText-Package HOWTO for Ruby on Rails first.

In this tutorial, I explain to localize LoginEngine plugin.

So you need to set up Rails Engines and LoginEngine first.

LoginEngine has its own database tables. Ruby-GetText-Package extracts the field names of these tables. So you need to create your database and database.yml, too.

The directories:

{RAILS_ROOT}/config/database.yml
{RAILS_ROOT}/vendor/plugins/login_engine

Add a Rakefile to the top of plugin directory.

desc "Create mo-files for L10n"
task :makemo do
  require 'gettext/utils'
  GetText.create_mofiles(true, "po", "locale")
end

$: << "../../../"
desc "Update pot/po files to match new version."
task :updatepo do
  require 'gettext/utils'
  GetText::ActiveRecordParser.init(:db_yml => "../../../config/database.yml")
  GetText.update_pofiles("login_engine", 
                         Dir.glob("{app,lib}/**/*.{rb,rhtml}"),
                         "login_engine 1.x.x")
end

The directories becomes:

{RAILS_ROOT}/config/database.yml
{RAILS_ROOT}/vendor/plugins/login_engine
                            +Rakefile

Translate all Controllers/Views/Models/Helpers like as Rails applications.

Controllers

Like Rails, set init_gettext the top of controllers.

class UserController < ApplicationController
  init_gettext "login_engine"
  model   :user

  def home
     :
     :
     @fullname = _("Not logged in...")
     :
     :

Models

Nothing special. In the Login Engine, you don't need to translate some fields and is required the field which is not in the database. So use untranslate and N_() methods here.

class User < ActiveRecord::Base
  include LoginEngine::AuthenticatedUser

  untranslate :salt, :salted_password, :verified, :role, :security_token,
              :token_expiry, :created_at, :updated_at, :logged_in_at,
              :deleted, :delete_after

  N_("User|Password")
end

Views

Just same as Rails views.

Next step is same as Rails, but in the plugin directory.

$ cd {RAILS_ROOT}/vendor/plugins/login_engine

To create po/login_engine.pot, run "updatepo" task.

$ rake updatepo

To create mo-files, run "makemo" task.

$ rake makemo

To update po/{lang}/blog.po, run "updatepo" task again.

$ rake updatepo

See HOWTO maintain po/mo files for more details.

Now the directory becomes like:

{RAILS_ROOT}/config/database.yml
{RAILS_ROOT}/vendor/plugins/login_engine
                           +app/controllers/user_controller.rb
                            +po/
                            +locale/
                            +Rakefile
                            +others

If you manage your plugin in SVN for installing it using script/plugin script, you need to import "locale" directory and all of mo-files into the repository. Because users(the application developers) don't run "rake makemo" when the plugin users download your plugin.

Here is the localized UserEngine v1.0.2 with Japanese locale.

login_engine_v1.0.2.gettext.tar.gz

2006-09-16 Added - Masao