Issue #3281570: Email PDF is generated empty

  commerce_ticketing.ticket_receipt_mail:

    class: Drupal\commerce_ticketing\Mail\TicketReceiptMail

    arguments: ['@logger.channel.commerce_ticketing', '@entity_type.manager', '@plugin.manager.mail', '@plugin.manager.entity_print.print_engine', '@entity_print.print_builder', '@renderer']

    arguments: ['@logger.channel.commerce_ticketing', '@entity_type.manager', '@plugin.manager.mail', '@plugin.manager.entity_print.print_engine', '@entity_print.print_builder', '@renderer', '@account_switcher', '@config.factory', '@language_manager']

  commerce_ticketing.uuid_param_converter:

    class: Drupal\commerce_ticketing\Routing\UuidParamConverter

namespace Drupal\commerce_ticketing\Mail;

use Drupal\commerce_ticketing\CommerceTicketInterface;

use Drupal\Core\Config\ConfigFactoryInterface;

use Drupal\Core\Entity\EntityTypeManagerInterface;

use Drupal\Core\Language\LanguageManagerInterface;

use Drupal\Core\Logger\LoggerChannelInterface;

use Drupal\Core\Mail\MailManagerInterface;

use Drupal\Core\Render\RendererInterface;

use Drupal\Core\Session\AccountSwitcherInterface;

use Drupal\Core\StringTranslation\StringTranslationTrait;

use Drupal\entity_print\Plugin\EntityPrintPluginManagerInterface;

use Drupal\entity_print\PrintBuilderInterface;

use Symfony\Component\HttpFoundation\StreamedResponse;

class TicketReceiptMail {

   */

  protected $renderer;

  /**

   * The account switcher service.

   *

   * @var \Drupal\Core\Session\AccountSwitcherInterface

   */

  protected $accountSwitcher;

  /**

   * The configuration factory.

   *

   * @var \Drupal\Core\Config\ConfigFactoryInterface

   */

  protected $configFactory;

  /**

   * The language manager.

   *

   * @var \Drupal\Core\Language\LanguageManagerInterface

   */

  protected $languageManager;

  /**

   * TicketReceiptMail constructor.

   *

   *   Entity Print builder.

   * @param \Drupal\Core\Render\RendererInterface $renderer

   *   The object renderer.

   * @param \Drupal\Core\Session\AccountSwitcherInterface $account_switcher

   *   The account switcher service.

   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory

   *   The configuration factory.

   * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager

   *   The language manager.

   */

  public function __construct(LoggerChannelInterface $logger, EntityTypeManagerInterface $entity_type_manager, MailManagerInterface $mail_manager, EntityPrintPluginManagerInterface $plugin_manager, PrintBuilderInterface $print_builder, RendererInterface $renderer) {

    $this->entityTypeManager = $entity_type_manager;

  public function __construct(LoggerChannelInterface $logger, EntityTypeManagerInterface $entity_type_manager, MailManagerInterface $mail_manager, EntityPrintPluginManagerInterface $plugin_manager, PrintBuilderInterface $print_builder, RendererInterface $renderer, AccountSwitcherInterface $account_switcher, ConfigFactoryInterface $config_factory, LanguageManagerInterface $language_manager) {

    $this->logger = $logger;

    $this->entityTypeManager = $entity_type_manager;

    $this->mailManager = $mail_manager;

    $this->pluginManager = $plugin_manager;

    $this->printBuilder = $print_builder;

    $this->renderer = $renderer;

    $this->accountSwitcher = $account_switcher;

    $this->configFactory = $config_factory;

    $this->languageManager = $language_manager;

  }

  /**

  public function send(CommerceTicketInterface $ticket, $to = NULL, $bcc = NULL) {

    try {

      $order = $ticket->getOrder();

      // If there's no recipient set, fallback to the ticket owner and then the

      // order owner.

      $to = $to ?? $ticket->getOwner()->getEmail() ?? $ticket->getOrder();

      $customer = $ticket->getOwner() ?? $order->getCustomer();

      $to = $to ?? $order->getEmail() ?? $customer->getEmail();

      if (!$to) {

        return FALSE;

      }

      // Default site langcode, if the ticket owner is not anonymous, use that

      // instead.

      $langcode = $this->languageManager->getCurrentLanguage()->getId();

      if ($customer->isAuthenticated()) {

        $langcode = $customer->getPreferredLangcode();

      }

      if ($ticket->hasTranslation($langcode)) {

        $ticket = $ticket->getTranslation($langcode);

      }

      $subject = $this->t('Ticket for your order #@number', ['@number' => $order->getOrderNumber()]);

      $body = $this->entityTypeManager->getViewBuilder('commerce_ticket')->view($ticket, 'receipt');

      $params = [

      ];

      $print_engine = $this->pluginManager->createSelectedInstance('pdf');

      $config = $this->configFactory->get('entity_print.settings');

      // We need to switch accounts to the customer so we can print the ticket

      // as if we were the user, otherwise it might try to print as anonymous

      // and show blank tickets.

      $this->accountSwitcher->switchTo($customer);

      // PDF generation inline so we don't have to deal with files.

      ob_start();

      $this->printBuilder->deliverPrintable([$ticket], $print_engine, TRUE);

      (new StreamedResponse(function () use ($ticket, $print_engine, $config) {

        $this->printBuilder->deliverPrintable([$ticket], $print_engine, FALSE, $config->get('default_css'));

      }))->send();

      $contents = ob_get_contents();

      ob_end_clean();

      $this->accountSwitcher->switchBack();

      $params['attachment'] = [

        'filename' => $ticket->uuid() . '.pdf',

        'filecontent' => $contents,

        'filemime' => 'application/pdf',

      ];

      // Default site langcode, if the ticket owner is not anonymous, use that

      // instead.

      $langcode = \Drupal::languageManager()->getCurrentLanguage()->getId();

      if ($ticket->getOwner()->isAuthenticated()) {

        $langcode = $ticket->getOwner()->getPreferredLangcode();

      }

      $result = $this->mailManager->mail('commerce_ticketing', 'ticket_receipt', $to, $langcode, $params, NULL, TRUE);

      $result = $this->mailManager->mail('commerce_ticketing', 'ticket_receipt', $to, $langcode, $params);

      if ($result['result']) {

        return TRUE;

      }