What steps are involved when adding Globalize to my Rails Project

I have a rails project that needs to be multi-lingual. I ran into a few issues while enabling globalize for my rails project.

I was wondering if there is a thorough checklist / recipe for enabling internationalisation for a rails app.

Please note that I use ActiveAdmin which needs to be part of this as well.

Installation

Set the locales you wish to support in your config/application.rb:

config.i18n.available_locales = [:de, :en]

Add migrations like described in the Globalize Readme

Make sure to remove NOT NULL constraints on columns that you're translating since they will be migrated over to the new translations table:

change_column :categories, :title, :string, null: true

Setting the locale

Detect the language based on the HTTP Accept Language Header:

application_controller.rb

# ...
def set_locale
  I18n.locale = extract_locale
end

def extract_locale
  headers = request.env['HTTP_ACCEPT_LANGUAGE'] || 'de'
  case headers.scan(/^[a-z]{2}/).first
    when 'en'
      'en'
    else
      'de'
  end
end

Empty '' translations

Globalize provides a fallback mechanism for missing translations. I was a bit surprised that some values didn't have a fallback on my front end. This was caused by blank values. To fix this I had to add the option fallbacks_for_empty_translations: true for the translates method call:

translates :title, :description, fallbacks_for_empty_translations: true

Note: This option can also used for the active_admin_translates method call.

ActiveRecord

Scopes and Queries

Scopes that use the translated fields have to be changed as well:

default_scope -> { order :title }

becomes:

default_scope -> { order('category_translations.title').includes(:translations) }

Active Admin

Setup

There is a gem that supports Globalize as well as ActiveAdmin:

# For Rails 4 use the master branch from github
gem "activeadmin-globalize", github: 'stefanoverna/activeadmin-globalize', branch: 'master'

Filters

Filters for translated attributes will no longer work by default:

filter :title

Will have to be changed to:

# as: :string is required otherwise the filter won't be shown
filter :translations_name, as: :string

Sorting

While the following works for translated columns:

# Admin: Categories.rb
index do
  column :title
end

As soon as we want to sort, there is an error, because the column title is not in the DB.

Update I only had this on certain models and it is not clear to me when this fails. So for some models I had to disable sorting:

column :title, sortable: false