Store the locale upon user registration

app/controllers/registrations_controller.rb

@@ -0,0 +1,25 @@
+class RegistrationsController < Devise::RegistrationsController
+  def create
+    build_resource(sign_up_params)
+
+    resource.language = I18n.locale
+
+    resource.save
+    yield resource if block_given?
+    if resource.persisted?
+      if resource.active_for_authentication?
+        set_flash_message :notice, :signed_up if is_flashing_format?
+        sign_up(resource_name, resource)
+        respond_with resource, location: after_sign_up_path_for(resource)
+      else
+        set_flash_message :notice, :"signed_up_but_#{resource.inactive_message}" if is_flashing_format?
+        expire_data_after_sign_in!
+        respond_with resource, location: after_inactive_sign_up_path_for(resource)
+      end
+    else
+      clean_up_passwords resource
+      set_minimum_password_length
+      respond_with resource
+    end
+  end
+end

config/routes.rb

@@ -1,5 +1,5 @@
 Rails.application.routes.draw do
-  devise_for :users
+  devise_for :users, controllers: {registrations: 'registrations'}
 
   scope module: :public do
     root to: 'home#index'