[Admin] Fix user locale handling in SolidusAdmin

admin/app/controllers/solidus_admin/base_controller.rb

@@ -5,29 +5,15 @@
 module SolidusAdmin
   class BaseController < ApplicationController
     include ActiveStorage::SetCurrent
-    include ::SolidusAdmin::Auth
     include Spree::Core::ControllerHelpers::Store
-    include Spree::Admin::SetsUserLanguageLocaleKey
+    include GearedPagination::Controller
 
+    include SolidusAdmin::ControllerHelpers::Auth
+    include SolidusAdmin::ControllerHelpers::Locale
     include SolidusAdmin::AuthAdapters::Backend if defined?(Spree::Backend)
 
-    include ::GearedPagination::Controller
-
-    before_action :set_locale
-
     layout 'solidus_admin/application'
     helper 'solidus_admin/container'
     helper 'solidus_admin/layout'
-
-    private
-
-    def set_locale
-      if params[:switch_to_locale].to_s != session[set_user_language_locale_key].to_s
-        session[set_user_language_locale_key] = params[:switch_to_locale]
-        flash[:notice] = t('spree.locale_changed')
-      end
-
-      I18n.locale = session[set_user_language_locale_key] ? session[set_user_language_locale_key].to_sym : I18n.default_locale
-    end
   end
 end

admin/app/controllers/solidus_admin/auth.rb → admin/app/controllers/solidus_admin/controller_helpers/auth.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-module SolidusAdmin::Auth
+module SolidusAdmin::ControllerHelpers::Auth
   extend ActiveSupport::Concern
 
   included do

admin/app/controllers/solidus_admin/controller_helpers/locale.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module SolidusAdmin::ControllerHelpers::Locale
+  extend ActiveSupport::Concern
+  include Spree::Admin::SetsUserLanguageLocaleKey
+
+  included do
+    before_action :set_locale
+    before_action :update_user_locale
+  end
+
+  private
+
+  def update_user_locale
+    requested_locale = params[:switch_to_locale] or return
+
+    if requested_locale.to_sym != user_locale
+      session[set_user_language_locale_key] = requested_locale
+
+      flash[:notice] = t('spree.locale_changed')
+      redirect_to url_for(request.params.except(:switch_to_locale))
+    end
+  end
+
+  def user_locale
+    session[set_user_language_locale_key] || I18n.default_locale
+  end
+
+  def set_locale
+    I18n.locale = user_locale
+  end
+end

admin/lib/solidus_admin/preview.rb

@@ -27,7 +27,7 @@ module ControllerHelper
     extend ActiveSupport::Concern
 
     included do
-      include SolidusAdmin::Auth
+      include SolidusAdmin::ControllerHelpers::Auth
       helper ActionView::Helpers
       helper SolidusAdmin::ContainerHelper
       helper_method :current_component