Issue #3240123: Allow CheckoutController to preserve query parameters upon redirect

modules/checkout/src/Controller/CheckoutController.php

@@ -18,6 +18,7 @@ use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Drupal\Core\Url;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\RedirectResponse;
+use Symfony\Component\HttpFoundation\RequestStack;
 
 /**
  * Provides the checkout form page.
@@ -56,6 +57,13 @@ class CheckoutController implements ContainerInjectionInterface {
    */
   protected $cartProvider;
 
+  /**
+   * Symfony Request Stack.
+   *
+   * @var \Symfony\Component\HttpFoundation\RequestStack
+   */
+  protected $requestStack;
+
   /**
    * Constructs a new CheckoutController object.
    *
@@ -69,13 +77,16 @@ class CheckoutController implements ContainerInjectionInterface {
    *   The cart session.
    * @param \Drupal\Core\Messenger\MessengerInterface $messenger
    *   The messenger.
+   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
+   *   Symfony Request Stack.
    */
-  public function __construct(CheckoutOrderManagerInterface $checkout_order_manager, FormBuilderInterface $form_builder, CartSessionInterface $cart_session, CartProviderInterface $cart_provider, MessengerInterface $messenger) {
+  public function __construct(CheckoutOrderManagerInterface $checkout_order_manager, FormBuilderInterface $form_builder, CartSessionInterface $cart_session, CartProviderInterface $cart_provider, MessengerInterface $messenger, RequestStack $request_stack) {
     $this->checkoutOrderManager = $checkout_order_manager;
     $this->formBuilder = $form_builder;
     $this->cartSession = $cart_session;
     $this->cartProvider = $cart_provider;
     $this->messenger = $messenger;
+    $this->requestStack = $request_stack;
   }
 
   /**
@@ -87,7 +98,8 @@ class CheckoutController implements ContainerInjectionInterface {
       $container->get('form_builder'),
       $container->get('commerce_cart.cart_session'),
       $container->get('commerce_cart.cart_provider'),
-      $container->get('messenger')
+      $container->get('messenger'),
+      $container->get('request_stack'),
     );
   }
 
@@ -134,7 +146,17 @@ class CheckoutController implements ContainerInjectionInterface {
     $requested_step_id = $route_match->getParameter('step');
     $step_id = $this->checkoutOrderManager->getCheckoutStepId($order, $requested_step_id);
     if ($requested_step_id != $step_id) {
-      $url = Url::fromRoute('commerce_checkout.form', ['commerce_order' => $order->id(), 'step' => $step_id]);
+      $url = Url::fromRoute('commerce_checkout.form',
+        [
+          'commerce_order' => $order->id(),
+          'step' => $step_id,
+        ],
+        [
+          'query' => [
+            $this->requestStack->getCurrentRequest()->query->all(),
+          ],
+        ],
+      );
       return new RedirectResponse($url->toString());
     }
     $checkout_flow = $this->checkoutOrderManager->getCheckoutFlow($order);