Add batch support

Hello
We have a problem with a large export, is it still in the roadmap to add batch support ?

thank you

Matthieu

Plus 1 on this! I have a client with many rows to export and it canney handle it.

After reviewing the source code, I'm not even sure how the action could be updated to work with Views Bulk Operations properly. The action just wants to stream it directly out.

+1 to this!

Very usefull with view.
Thank you

This is my controller to generate PDF view with batch

  /**
   * Starts the batch process to flush image styles.
   */
  public function generate() {

    $destination = \Drupal::request()->get('destination');

    // Create a new batch builder.
    $batch_builder = new BatchBuilder();

    // Set batch title and messages.
    $batch_builder->setTitle($this->t('Generating PDF'))
      ->setInitMessage($this->t('Starting generating PDF...'))
      ->setProgressMessage($this->t('Generate PDF.'))
      ->setErrorMessage($this->t('An error occurred during the generating process.'));

    // Add a batch operation 
    $batch_builder->addOperation([__CLASS__, 'buildPDF'], [$destination]);

    // Set a callback to handle completion.
    $batch_builder->setFinishCallback([__CLASS__, 'finishBatch']);

    // Set the batch.
    batch_set($batch_builder->toArray());

    // Return a redirect to the batch processing page.
    return batch_process();
  }

  /**
   * Flushes a single image style.
   *
   * @param string $style_name
   *   The name of the image style to be flushed.
   * @param array $context
   *   The batch context.
   */
  public static function buildPDF($destination, &$context) {

    // Initialize progress counter, which will keep track of how many items
    // we've processed.
    $context['sandbox']['progress'] = 0;

    $context['results'] = [
      'automatic_download' => TRUE,
      'redirect_url' => $destination,
    ];

    $export_type = 'pdf';
    $view_name = '<view_name>';
    $display_id = 'page_1';

    // Create the Print engine plugin.
    $config = \Drupal::config('entity_print.settings');
    $view = \Drupal::entityTypeManager()->getStorage('view')->load($view_name);
    
    $executable = $view->getExecutable();
    $executable->setDisplay($display_id);

    $scheme = 'public';
    $filename = 'pdf_catalog/name.pdf'; 

    $print_engine = \Drupal::service('plugin.manager.entity_print.print_engine')->createSelectedInstance($export_type);
    // The Print is sent straight to the browser.
    $path = \Drupal::service('entity_print.print_builder')->savePrintable([$view], $print_engine, $scheme, $filename);

    $context['sandbox']['progress'] = 1;
    $context['results']['vde_file'] = $path;
    $context['finished'] = 1;
  }

  /**
   * Callback to handle batch completion.
   *
   * @param bool $success
   *   Whether the batch process was successful.
   * @param array $results
   *   The batch results.
   * @param array $operations
   *   The remaining batch operations.
   */
  public static function finishBatch($success, $results, $operations) {

    // Set Drupal status message to let the user know the results of the export.
    // The 'success' parameter means no fatal PHP errors were detected.
    // All other error management should be handled using 'results'.
    $response = new RedirectResponse($results['redirect_url']);
    if ($success && isset($results['vde_file']) && file_exists($results['vde_file'])) {
      // Check the permissions of the file to grant access and allow
      // modules to hook into permissions via hook_file_download().
      $headers = \Drupal::moduleHandler()->invokeAll('file_download', [$results['vde_file']]);

      // Require at least one module granting access and none denying access.

      // Create a web server accessible URL for the private file.
      // Permissions for accessing this URL will be inherited from the View
      // display's configuration.
      $url = \Drupal::service('file_url_generator')->generateAbsoluteString($results['vde_file']);
      $message = t('Export complete. Download the file <a target="_blank" download href=":download_url"  data-download-enabled="false" id="vde-automatic-download">here</a>.', [':download_url' => $url]);
      // If the user specified instant download than redirect to the file.
      if ($results['automatic_download']) {

        // Prevents browser from displaying JSON data if automatic download
        // is selected.
        if (!preg_match("/^.*\.(json)$/i", $results['vde_file'])) {
          $message = t('Export complete. Download the file <a target="_blank" download href=":download_url" data-download-enabled="true" id="vde-automatic-download">here</a> if file is not automatically downloaded.', [':download_url' => $url]);
        }
      }

      \Drupal::messenger()->addMessage($message);
      return $response;
    }
    else {
      $message = t('Export failed. Make sure the private file system is configured and check the error log.');
      \Drupal::messenger()->addError($message);
      return $response;
    }

  }