expo qr code to get visitors email

web/modules/custom/materio_expo/src/Controller/QRController.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace Drupal\materio_expo\Controller;
+
+use Drupal\Core\Controller\ControllerBase;
+use Symfony\Component\HttpFoundation\RedirectResponse;
+use Drupal\Core\Url;
+
+/**
+ * Class QRController.
+ */
+class QRController extends ControllerBase {
+
+  /**
+   * Hello.
+   *
+   * @return string
+   *   Return Hello string.
+   */
+  public function getfile($ref) {
+    //? https://drupal.stackexchange.com/questions/255216/how-to-do-a-redirectresponse-with-a-destination-query-parameter
+
+    //* get node from ref
+    $entity_storage = \Drupal::entityTypeManager()->getStorage('node');
+    $query = $entity_storage->getQuery()
+      ->condition('type', 'materiau')
+      ->condition('status', '1')
+      ->condition('field_reference', $ref);
+    $results = $query->execute();
+    $nid = array_pop($results);
+    $node = $entity_storage->load($nid);
+
+    //* get file from node
+    $file = $node->get('field_fiche_expo')->referencedEntities()[0];
+
+    //* redirect to file
+    return new RedirectResponse($file->createFileUrl());
+
+    // return [
+    //   '#type' => 'markup',
+    //   '#markup' => $this->t("Implement method: getfile with parameter(s): $ref"),
+    // ];
+  }
+
+}