My presentation on I18n during Ruby India Conference 2010, Bangalore, India

1. The Ruby on Rails I18n Core API PRESENTED BY -Neeraj Kumar

9. before_filter :set_locale def set_locale # if params[:locale] is nil then I18n.default_locale will be used I18n .locale = params[ :locale ] end - URL : http://example.com/books?locale=pt - will load Portuguese localization.

11. # app/controllers/application_controller.rb def default_url_options (options = {}) logger.debug “default_url_options is passed options: #{options.inspect}” { :locale => I18n .locale} end - Every helper method dependent on url_for automatically include the locale in the query string .

12. # config/routes.rb map.resources :books , :path_prefix => '/:locale' # => www.example.com/nl/books map.root '/:locale' , :controller => “dashboard”

13. - Drawback of default_url_options implementation pass the :id option, e.g. link_to 'show', book_url(:id => book)

15. before_filter :set_locale def set_locale I18n .locale = extract_locale_from_uri end

16. def extract_locale_from_tld parsed_locale = request.host.split( '.' ).last I18n .available_locales.include?(parsed_locale.to_sym) ? parsed_locale : nil end - parsed_locale = request.host.split('.').first to set the locale from subdomain.

18. def set_locale logger.debug = “* Accept-Language: #{request.env['HTTP_ACCEPT_LANGUAGE']}” I18n .locale = extract_locale_from_accept_language_header end

19. def extract_locale_from_accept_language_header request.env[ 'HTTP_ACCEPT_LANGUAGE' ].scan( /^[a-z]{2}/ ).first end - Using GeoIP (or similar) Database – GeoIP Lite Country - User Profile

25. Anatomy of Gem i18n i18n backend core_ext helpers locales backend exceptions gettext helpers locale i18n version locale gettext fallbacks tag

26. active_record Interpolation compiler Interpolation compiler Interpolation compiler Interpolation compiler Interpolation compiler Interpolation compiler Interpolation compiler fast gettext helpers Interpolation compiler links metadata simple active_record base cache cascader chain cldr fallbacks pluralization missing translation store_procs backend

30. i18n.rb def available_locales @@available_locales ||= backend.available_locales end

33. I18n.rb def default_exception_handler (exception, locale, key, options) return exception.message if MissingTranslationData === exception raise exception end

43. base.rb def store_translations (locale, data, options = {}) merge_translations(locale, data, options) end

45. base.rb def translate (locale, key, options = {}) raise InvalidLocale .new(locale) unless locale return key.map { |k| translate(locale, k, options) } if key.is_a?( Array ) if options.empty? entry = resolve(locale, key, lookup(locale, key), options) raise ( I18n::MissingTranslationData .new(locale, key, options)) if entry.nil?

46. else count, scope, default = options.values_at( :count , :scope , :default ) values = options.reject { |name, value| RESERVED_KEYS .include?(name) } entry = lookup(locale, key, scope, options) entry = entry.nil? && default ? default(locale, key, default, options) : resolve(locale, key, entry, options) base.rb

47. raise ( I18n::MissingTranslationData .new(locale, key, options)) if entry.nil? e ntry = pluralize(locale, entry, count) if count entry = interpolate(locale, entry, values) if values end entry end base.rb

50. when '%B' then I18n.t(: &quot;date.month_names&quot; , :locale => locale, :format => format)[object.mon] when '%p' then I18n.t(: &quot;time.#{object.hour < 12 ? :am : :pm}&quot; , :locale => locale, :format => format) if object.respond_to? :hour end base.rb

53. - customization – e.g. the default exception handling does not allow to catch missing translation during automated test easily .

55. module I18n def just_raise_that_exception (*args) raise args.first end end I18n .exception_handler = :just_raise_that_exception