globalize: A Ruby repository from lambda2

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Globalize builds on the I18n API in Ruby on Rails to add model translations to ActiveRecord models.

In other words, a way to translate actual user-generated content, for example; a single blog post with multiple translations.

Requirements

ActiveRecord >= 4.2.0 (see below for installation with ActiveRecord 3.x)
I18n

Installation

To install the ActiveRecord 4.2.x compatible version of Globalize with its default setup, just use:

gem install globalize

When using bundler put this in your Gemfile:

gem 'globalize', '~> 5.1.0'

Please help us by letting us know what works, and what doesn't, when using pre-release code.

Put in your Gemfile

gem 'globalize', git: 'https://github.com/globalize/globalize'
gem 'activemodel-serializers-xml'

To use the version of globalize for ActiveRecord 4.0 or 4.1, specify:

gem 'globalize', '~> 4.0.3'

To use the version of globalize for ActiveRecord 3.1 or 3.2, specify:

gem 'globalize', '~> 3.1.0'

(If you are using ActiveRecord 3.0, use version 3.0: gem 'globalize', '3.0.4'.)

The 3-1-stable branch of this repository corresponds to the latest ActiveRecord 3 version of globalize. Note that globalize3 has been deprecated and you are encouraged to update your Gemfile accordingly.

Model translations

Model translations allow you to translate your models' attribute values. E.g.

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

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

I18n.locale = :en
post.title # => Globalize rocks!

I18n.locale = :he
post.title # => גלובאלייז2 שולט!

You can also set translations with mass-assignment by specifying the locale:

post.attributes = { title: 'גלובאלייז2 שולט!', locale: :he }

In order to make this work, you'll need to add the appropriate translation tables. Globalize comes with a handy helper method to help you do this. It's called create_translation_table!. Here's an example:

Note that your migrations can use create_translation_table! and drop_translation_table! only inside the up and down instance methods, respectively. You cannot use create_translation_table! and drop_translation_table! inside the change instance method.

Creating translation tables

Also note that before you can create a translation table, you have to define the translated attributes via translates in your model as shown above.

class CreatePosts < ActiveRecord::Migration
  def change
    create_table :posts do |t|
      t.timestamps
    end

    reversible do |dir|
      dir.up do
        Post.create_translation_table! :title => :string, :text => :text
      end

      dir.down do
        Post.drop_translation_table!
      end
    end
  end
end

Also, you can pass options for specific columns. Here’s an example:

class CreatePosts < ActiveRecord::Migration
  def change
    create_table :posts do |t|
      t.timestamps
    end

    reversible do |dir|
      dir.up do
        Post.create_translation_table! :title => :string,
          :text => {:type => :text, :null => false, :default => 'abc'}
      end

      dir.down do
        Post.drop_translation_table!
      end
    end
  end
end

Note that the ActiveRecord model Post must already exist and have a translates directive listing the translated fields.

Migrating existing data to and from the translated version

As well as creating a translation table, you can also use create_translation_table! to migrate across any existing data to the default locale. This can also operate in reverse to restore any translations from the default locale back to the model when you don't want to use a translation table anymore using drop_translation_table!

This feature makes use of untranslated_attributes which allows access to the model's attributes as they were before the translation was applied. Here's an example (which assumes you already have a model called Post and its table exists):

class TranslatePosts < ActiveRecord::Migration
  def change
    reversible do |dir|
      dir.up do
        Post.create_translation_table!({
          :title => :string,
          :text => :text
        }, {
          :migrate_data => true
        })
      end

      dir.down do
        Post.drop_translation_table! :migrate_data => true
      end
    end
  end
end

NOTE: Make sure you drop the translated columns from the parent table after all your data is safely migrated.

To automatically remove the translated columns from the parent table after the data migration, please use option remove_source_columns.

class TranslatePosts < ActiveRecord::Migration
  def self.up
    Post.create_translation_table!({
      :title => :string,
      :text => :text
    }, {
      :migrate_data => true,
      :remove_source_columns => true
    })
  end

  def self.down
    Post.drop_translation_table! :migrate_data => true
  end
end

In order to use a specific locale for migrated data, you can use I18n.with_locale:

    I18n.with_locale(:bo) do
      Post.create_translation_table!({
        :title => :string,
        :text => :text
      }, {
        :migrate_data => true
      })
    end

Adding additional fields to the translation table

In order to add a new field to an existing translation table, you can use add_translation_fields!:

class AddAuthorToPost < ActiveRecord::Migration
  def change
    reversible do |dir|
      dir.up do
        Post.add_translation_fields! author: :text
      end

      dir.down do
        remove_column :post_translations, :author
      end
    end
  end
end

NOTE: Remember to add the new field to the model:

translates :title, :author

Gotchas

Because globalize uses the :locale key to specify the locale during mass-assignment, you should avoid having a locale attribute on the parent model.

If you like your translated model to update if a translation changes, use the touch: true option together with translates:

  translates :name, touch: true

Known Issues

If you're getting the ActiveRecord::StatementInvalid: PG::NotNullViolation: ERROR: null value in column "column_name" violates not-null constraint error, the only known way to deal with it as of now is to remove not-null constraint for the globalized columns:

class RemoveNullConstraintsFromResourceTranslations < ActiveRecord::Migration
  def change
    change_column_null :resource_translations, :column_name, true
  end
end

Versioning with Globalize

See the globalize-versioning gem.

I18n fallbacks for empty translations

It is possible to enable fallbacks for empty translations. It will depend on the configuration setting you have set for I18n translations in your Rails config.

You can enable them by adding the next line to config/application.rb (or only config/environments/production.rb if you only want them in production)

# For version 1.1.0 and above of the `i18n` gem:
config.i18n.fallbacks = [I18n.default_locale]
# Below version 1.1.0 of the `i18n` gem:
config.i18n.fallbacks = true

By default, globalize will only use fallbacks when your translation model does not exist or the translation value for the item you've requested is nil. However it is possible to also use fallbacks for blank translations by adding :fallbacks_for_empty_translations => true to the translates method.

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

puts post.translations.inspect
# => [#<Post::Translation id: 1, post_id: 1, locale: "en", title: "Globalize rocks!", name: "Globalize">,
      #<Post::Translation id: 2, post_id: 1, locale: "nl", title: '', name: nil>]

I18n.locale = :en
post.title # => 'Globalize rocks!'
post.name  # => 'Globalize'

I18n.locale = :nl
post.title # => ''
post.name  # => 'Globalize'

class Post < ActiveRecord::Base
  translates :title, :name, :fallbacks_for_empty_translations => true
end

puts post.translations.inspect
# => [#<Post::Translation id: 1, post_id: 1, locale: "en", title: "Globalize rocks!", name: "Globalize">,
      #<Post::Translation id: 2, post_id: 1, locale: "nl", title: '', name: nil>]

I18n.locale = :en
post.title # => 'Globalize rocks!'
post.name  # => 'Globalize'

I18n.locale = :nl
post.title # => 'Globalize rocks!'
post.name  # => 'Globalize'

Fallback locales to each other

It is possible to setup locales to fallback to each other.

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

Globalize.fallbacks = {:en => [:en, :pl], :pl => [:pl, :en]}

I18n.locale = :en
en_post = Post.create(:title => 'en_title')

I18n.locale = :pl
pl_post = Post.create(:title => 'pl_title')
en_post.title # => 'en_title'

I18n.locale = :en
en_post.title # => 'en_title'
pl_post.title # => 'pl_title'

Scoping objects by those with translations

To only return objects that have a translation for the given locale we can use the with_translations scope. This will only return records that have a translations for the passed in locale.

Post.with_translations('en')
# => [
  #<Post::Translation id: 1, post_id: 1, locale: "en", title: "Globalize rocks!", name: "Globalize">,
  #<Post::Translation id: 2, post_id: 1, locale: "nl", title: '', name: nil>
]

Post.with_translations(I18n.locale)
# => [
  #<Post::Translation id: 1, post_id: 1, locale: "en", title: "Globalize rocks!", name: "Globalize">,
  #<Post::Translation id: 2, post_id: 1, locale: "nl", title: '', name: nil>
]

Post.with_translations('de')
# => []

Show different languages

In views, if there is content from different locales that you wish to display, you should use the with_locale option with a block, as below:

<% Globalize.with_locale(:en) do %>
  <%= render "my_translated_partial" %>
<% end %>

Your partial will now be rendered with the :en locale set as the current locale.

Interpolation

Globalize supports interpolation in a similar manner to I18n.

class Post < ActiveRecord::Base
  translates :title
end

I18n.locale = :en
post.title = "Globalize %{superlative}!"

post.title
# #=> "Globalize %{superlative}!"

post.title(:foo => "bar")
# SomeError: missing interpolation argument :superlative

post.title(:superlative => "rocks")
# #=> "Globalize rocks!"

Fragment caching

Don't forget to add globalize locale into the cache_key to separate different localizations of the record. One of the possible ways to implement it:

# inside translated model
def cache_key
  super + '-' + Globalize.locale.to_s
end

Thread-safety

Globalize uses request_store gem to clean up thread-global variable after every request. RequestStore includes a Railtie that will configure everything properly for Rails 3+ apps.

If you're not using Rails, you may need to consult a RequestStore's README to configure it.

Tutorials and articles

Go Global with Rails and I18n - introductory article about i18n in Rails (Ilya Bodrov)

Official Globalize extensions

globalize-accessors - generator of accessor methods for models. (e.g. title_en, title_cz)
globalize-versioning - versioning support for using Globalize with paper_trail. (compatible with Globalize 3.x and 4.x)

Alternative solutions

Traco - use multiple columns in the same model (Barsoom)
Mobility - pluggable translation framework supporting many strategies, including translatable columns, translation tables and hstore/jsonb (Chris Salzberg)
hstore_translate - use PostgreSQL's hstore datatype to store translations, instead of separate translation tables (Cédric Fabianski)
json_translate - use PostgreSQL's json/jsonb datatype to store translations, instead of separate translation tables (Cédric Fabianski)
Trasto - store translations directly in the model in a Postgres Hstore column

lambda2/globalize