SessionExampleController.php

<?php

namespace Drupal\session_example\Controller;

use Drupal\Core\Controller\ControllerBase;
use Symfony\Component\HttpFoundation\Request;

/**
 * Controller for a page to display the session information.
 *
 * @ingroup session_example
 */
class SessionExampleController extends ControllerBase {
    
    /**
     * Display the example session information.
     *
     * By default, controller methods receive a Request object as a parameter, so
     * we can use one here.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request object.
     *
     * @return string
     *   A renderable array containing the user information from the session.
     */
    public function showSession(Request $request) {
        // Get the session from the request object.
        $session = $request->getSession();
        // Make a table of the session information.
        $row = [];
        foreach ([
            'name',
            'email',
            'quest',
            'color',
        ] as $item) {
            $key = "session_example.{$item}";
            // Get the session value, with a default of 'No name' etc. for each type
            // of information we have.
            $row[0][$item] = $session->get($key, $this->t('No @type', [
                '@type' => $item,
            ]));
        }
        return [
            // Since this page will be cached, we have to manage the caching. We'll
            // use a cache tag and manage it within the session helper. We use the
            // session ID to guarantee a unique tag per session. The submission form
            // will manage invalidating this tag.
'#cache' => [
                'tags' => [
                    'session_example:' . $session->getId(),
                ],
            ],
            'description' => [
                '#type' => 'item',
                '#title' => $this->t('Saved Session Keys'),
                '#markup' => $this->t('The example form lets you set some session keys.  This page lists their current values.'),
            ],
            'session_status' => [
                '#type' => 'table',
                '#header' => [
                    $this->t('Name'),
                    $this->t('Email'),
                    $this->t('Quest'),
                    $this->t('Color'),
                ],
                '#rows' => $row,
            ],
        ];
    }

}