ModelTranslations

Minimal implementation of Globalize2 style model translations. Rails 2.2 is required.

Installation

Gem:

in config/environment.rb:

config.gem 'model_translations', :source => 'http://gemcutter.org'

Plugin:

script/plugin install git://github.com/guillaumegentil/model_translations.git

Implementation

class Post < ActiveRecord::Base
  translates :title, :text
end

Allows you to translate values for the attributes :title and :text per locale:

I18n.locale = :en
post.title # ModelTranslations rocks!
I18n.locale = :sv
post.title # Rockar fett!

In order to make this work you need to take care of creating the appropriate database migrations manually. The migration for the above Post model could look like this:

class CreatePosts < ActiveRecord::Migration
  def self.up
    create_table :posts do |t|
      t.timestamps
    end
    create_table :post_translations do |t|
      t.string     :locale
      t.references :post
      t.string     :title
      t.text       :text
      t.timestamps
    end
  end
  def self.down
    drop_table :posts
    drop_table :post_translations
  end
end

To migrate from a model with existing attributes to one with translated attributes the migration could look like this.

class RemoveTitleTextFromPosts < ActiveRecord::Migration
  def self.up
    [:title, :text].each do |attribute|
      Post.all.each{|post| post.update_attribute(attribute, post.read_attribute(attribute)) }
      remove_column :post, attribute
    end
  end
  def self.down
    add_column :post, :title, :string
    add_column :post, :text, :text
    [:title, :text].each do |attribute|
      Post.all.each{|post| post.write_attribute(attribute, post.send(attribute)); post.save}
    end
  end
end

Advanced Querying

All models that have translations are hooked up with a has_many :translations association for their corresponding translation table. Use this to your advantage.

Note that the following example requires Rails 2.3 since default_scope is used.

class Post < ActiveRecord::Base
  translates :title, :text

  default_scope :include => :translations

  named_scope :translated, lambda { { :conditions => { 'post_translations.locale' => I18n.locale.to_s } } }
  named_scope :ordered_by_title, :order => 'post_translations.title'
  named_scope :with_title, lambda { |title| { :conditions => { 'post_translations.title' => title } } }
end

Post.translated.ordered_by_title # All posts with the current locale sorted on title
Post.with_title('My translated title') # Equivalent to Post.find_all_by_title

As you can see including the model_translations on all querys by default gives us (apart from reducing the number of querys to the database) the possibility of using the post_translations table for further query customization.