How to change the locale through URL?

Question

In my bi-lingual Rails 4 application I have a LocalesController like this:

class LocalesController < ApplicationController

  def change_loca         


        

Answer 1

This is how I did it in one of Rails 4 applications:

in config/routes.rb:

Rails.application.routes.draw do
  scope "(:locale)", locale: /#{I18n.available_locales.join("|")}/ do
    # rest of your routes here
    # for example:
    resources :projects
  end
end

make sure in config/environments/production.rb this line is uncommented:

config.i18n.fallbacks = true

If you wish to have a default_locale setup other than :en, then in config/application.rb, uncomment this line:

config.i18n.default_locale = :de # and then :de will be used as default locale

Now, last part of your setup, add this method in ApplicationController:

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception

  before_action :set_locale

  private
    def set_locale
      I18n.locale = params[:locale] || session[:locale] || I18n.default_locale
      session[:locale] = I18n.locale
    end

   def default_url_options(options={})
     logger.debug "default_url_options is passed options: #{options.inspect}\n"
     { locale: I18n.locale }
   end
end

Now, your application can be accessed as: http://localhost:3000/en/projects, http://localhost:3000/fr/projects, or http://localhost:3000/projects. The last one http://localhost:3000/projects will use :en as its default locale(unless you make that change in application.rb).