= ModelTranslations

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

== Installation

  script/plugin install git://github.com/janne/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 :model_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 => :model_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.


Copyright (c) 2008 Jan Andersson, released under the MIT license