Add i18n helper for controllers to switch language by params

app/controllers/base_controller.rb

@@ -8,6 +8,7 @@ class BaseController < ApplicationController
   include Spree::Core::ControllerHelpers::Order
   include Spree::Core::ControllerHelpers::RespondWith
 
+  include I18nHelper
   include EnterprisesHelper
   include OrderCyclesHelper
 
@@ -17,9 +18,9 @@ class BaseController < ApplicationController
   # include Spree::ProductsHelper so that method is available on the controller
   include Spree::ProductsHelper
 
+  before_filter :set_locale
   before_filter :check_order_cycle_expiry
 
-
   private
 
   def set_order_cycles

app/controllers/spree/admin/base_controller_decorator.rb

@@ -1,6 +1,9 @@
 require 'spree/core/controller_helpers/respond_with_decorator'
 
 Spree::Admin::BaseController.class_eval do
+  include I18nHelper
+
+  before_filter :set_locale
   before_filter :warn_invalid_order_cycles
 
   # Warn the user when they have an active order cycle with hubs that are not ready

app/helpers/i18n_helper.rb

@@ -0,0 +1,7 @@
+module I18nHelper
+  private
+
+  def set_locale
+    I18n.locale = params[:locale] || I18n.default_locale
+  end
+end