HasTranslations

This simple plugin creates translations for your model. Uses delegation pattern: http://en.wikipedia.org/wiki/Delegation_pattern

Tested with ActiveRecord versions: 3.2.x, 4.0.x, 4.1.x, 4.2.x, 5.0.x And tested with ruby 1.9.3, 2.0.0, 2.1.x, 2.2.x, 2.3.x

Compatibility

This version only support Rails 4.x.x and 3.2.x. For Rails 2.3.x support please get the 0.3.5 version of this gem and for Rails 3.1.x get the 1.0.0 of this gem. Plugin support is deprecated in Rails and will be removed soon so this version drop plugin support. To prevent method shadowing between "translations" class method and "translations" relation in models the class method has been renamed has_translations.

class Article < ActiveRecord::Base
  translations :title, :text
end

become

class Article < ActiveRecord::Base
  has_translations :title, :text
end

Installation

gem install has_translations

Example

For example you have Article model and you want to have title and text to be translated.

Run in command line:

rails g translation_for article title:string text:text

It will produce ArticleTranslation model and migration.

Add to article model translations :value1, :value2:

class Article < ActiveRecord::Base
  has_translations :title, :text
end

And that's it. Now you can add your translations using:

article = Article.create

article.translations.create(:locale => 'en', :title => 'title', :text => 'text') # or ArticleTranslation.create(:article => article, :locale => 'en', :title => 'title', :text => 'text')
article.translations.create(:locale => 'ru', :title => 'заголовок', :text => 'текст')
article.reload # reload cached translations association array
I18n.locale = :en
article.text # text
I18n.locale = :ru
article.title # заголовок

You can use text filtering plugins, like acts_as_sanitiled and validations, and anything else that is available to the ActiveRecord:

class ArticleTranslation < ActiveRecord::Base
  acts_as_sanitiled :title, :text

  validates_presence_of :title, :text
  validates_length_of :title, :maximum => 100
end

Options:

:fallback => true [default: false] - fallback 1) default locale; 2) first from translations;
:reader => false [default: true] - add reader to the model object
:writer => true [default: false] - add writer to the model object
:autosave => true [default: false] - use autosave option for the ActiveRecord translations relation
:nil => nil [default: ''] - if no model found by default returns empty string, you can set it for example to nil (no lambda supported)
:foreign_key => nil [default: nil] - add the foreign_key for has_many and belogns_to associations

It's better to use translations with accepts_nested_attributes_for:

accepts_nested_attributes_for :translations

To create a form for this you can use all_translations method. It's have all the locales that you have added using the I18n.available_locales= method. If translation for one of the locale isn't exists, it will build it with :locale. So an example which I used in the production (using formtastic gem):

<% semantic_form_for [:admin, @article] do |f| %>
  <%= f.error_messages %>

  <% f.inputs :name => "Basic" do %>
    <% object.all_translations.values.each do |translation| %>
      <% f.semantic_fields_for :translations, translation do |ft| %>
        <%= ft.input :title, :label => "Title #{ft.object.locale.to_s.upcase}" %>
        <%= ft.input :text, :label => "Text #{ft.object.locale.to_s.upcase}" %>
        <%= ft.input :locale, :as => :hidden %>
      <% end %>
    <% end %>
  <% end %>
<% end %>

Sometimes you have validations in the translation model, and if you want to skip the translations that you don't want to add to the database, you can use :reject_if option, which is available for the accepts_nested_attributes_for:

accepts_nested_attributes_for :translations, :reject_if => lambda { |attrs| attrs['title'].blank? && attrs['text'].blank? }

named_scope translated(locale) - with that named_scope you can find only those models that is translated only to specific locale. For example if you will have 2 models, one is translated to english and the second one isn't, then it Article.translated(:en) will find only first one.

TODO

caching
write more examples: fallback feature
write blog post about comparison and benefits of this plugin between another translation model plugins

Alternatives

I know three of them:

globalize3 - Globalize3 is the successor of Globalize for Rails.
puret - special for Rails 3 and almost the same as this project.
model_translations - almost the same as this project, but more with more code in lib.
translatable_columns - different approach: every column have own postfix "_#locale" in the same table (sometimes it could be fine).