Example of how to get you application display content with the proper locale.

Introduction

Let's say that you want to your user to set his/her locale using a drop down menu and save the locale in the session. If the user didn't set a locale you want to check on the browser settings, and if nothing matches we'll fall back to the default language.

(see the demo app for a implementation)

If someone is interested in creating a helper, please submit your patch to me.

Details

We'll just create an around_filter in app/controllers/application.rb

  class ApplicationController < ActionController::Base
  helper :all # include all helpers, all the time
  around_filter :set_locale

  private

  # Set the locale from the parameters, the session, or the navigator
  # If none of these works, the Globalite default locale is set (en-*)
  def set_locale
    # Get the current path and request method (useful in the layout for changing the language)
    @current_path = request.env['PATH_INFO']
    @request_method = request.env['REQUEST_METHOD']

    # Try to get the locale from the parameters, from the session, and then from the navigator
    if params[:user_locale]
        logger.debug "[globalite] #{params[:user_locale][:code]} locale passed"
        Locale.code = params[:user_locale][:code] #get_matching_ui_locale(params[:user_locale][:code]) #|| session[:locale] || get_valid_lang_from_accept_header || Globalite.default_language
        # Store the locale in the session
        session[:locale] = Locale.code
    elsif session[:locale]
        logger.debug "[globalite] loading locale: #{session[:locale]} from session"
        Locale.code = session[:locale]
    else
        logger.debug "[globalite] found a valid http header locale: #{get_valid_lang_from_accept_header}"
        Locale.code = get_valid_lang_from_accept_header
    end
    
    logger.debug "[globalite] Locale set to #{Locale.code}"
    # render the page
    yield

    # reset the locale to its default value
    Locale.reset!
  end

  # Get a sorted array of the navigator languages
  def get_sorted_langs_from_accept_header
    accept_langs = request.env['HTTP_ACCEPT_LANGUAGE'].split(/,/) rescue nil
    return nil unless accept_langs

    # Extract langs and sort by weight
    # Example HTTP_ACCEPT_LANGUAGE: "en-au,en-gb;q=0.8,en;q=0.5,ja;q=0.3"
    wl = {}
    accept_langs.each {|accept_lang|
        if (accept_lang + ';q=1') =~ /^(.+?);q=([^;]+).*/
            wl[($2.to_f rescue -1.0)]= $1
        end
    }
    logger.debug "[globalite] client accepted locales: #{wl.sort{|a,b| b[0] <=> a[0] }.map{|a| a[1] }.to_sentence}"
    sorted_langs = wl.sort{|a,b| b[0] <=> a[0] }.map{|a| a[1] }
  end

  # Returns a valid language that best suits the HTTP_ACCEPT_LANGUAGE request header.
  # If no valid language can be deduced, then <tt>nil</tt> is returned.
  def get_valid_lang_from_accept_header
    # Get the sorted navigator languages and find the first one that matches our available languages
    get_sorted_langs_from_accept_header.detect{|l| get_matching_ui_locale(l) }
  end

  # Returns the UI locale that best matches with the parameter
  # or nil if not found
  def get_matching_ui_locale(locale)
    lang = locale[0,2].downcase
    if locale[3,5]
      country = locale[3,5].upcase
      logger.debug "[globalite] trying to match locale: #{lang}-#{country}"
      locale_code = "#{lang}-#{country}".to_sym
    else
      logger.debug "[globalite] trying to match #{lang}-*"
      locale_code = "#{lang}-*".to_sym
    end

    # Check with exact matching
    if Globalite.ui_locales.values.include?(locale)
      logger.debug "[globalite] Globalite does include #{locale}"
      locale_code
    end

    # Check on the language only
    Globalite.ui_locales.values.each do |value|
      value.to_s =~ /#{lang}-*/ ? value : nil
    end
  end

end