Fetch a random node by type and return it as a JSON response.

SurpriseMeController.php

<?php

declare(strict_types = 1);

namespace Drupal\harlib_surprise_me\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\node\Entity\Node;
use Symfony\Component\HttpFoundation\JsonResponse;

/**
 * Class SurpriseMeController.
 */
class SurpriseMeController extends ControllerBase {

  /**
   * Return a random collection node as a JSON object.
   *
   * @return \Symfony\Component\HttpFoundation\JsonResponse
   *   The node information.
   *
   * @throws \Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException
   * @throws \Drupal\Core\Entity\EntityMalformedException
   */
  public function surprise() : JsonResponse {
    $nid = $this->getRandomCollection();
    $node = $this->entityTypeManager()->getStorage('node')->load($nid);

    $node = [
      'id' => $node->id(),
      'title' => $node->getTitle(),
      'url' => $node->toUrl()->toString(),
      'card_type' => $node->get('field_directory_view')->value
    ];

    $response = new JsonResponse($node);
    $response->setMaxAge(30);
    $response->setSharedMaxAge(30);
    $response->setPublic();

    return $response;
  }

  /**
   * Query for collections and return a random one.
   *
   * @return int
   *   The random node id.
   *
   * @throws \Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException
   */
  protected function getRandomCollection() {
    $query = $this->entityTypeManager()->getStorage('node')->getQuery();
    $query->condition('type', 'collection');
    $query->condition('status', Node::PUBLISHED);
    $query->condition('field_show_in_listing', TRUE);
    $results = $query->execute();

    $results = array_values($results);
    $key = array_rand($results);

    return $results[$key];
  }

}