OpmlFeedAdd::submitForm

public OpmlFeedAdd::submitForm(array &$form, FormStateInterface $form_state)

public function submitForm(array &$form, FormStateInterface $form_state) {
  $validators = array('file_validate_extensions' => array('opml xml'));
  if ($file = file_save_upload('upload', $validators, FALSE, 0)) {
    $data = file_get_contents($file->getFileUri());
  }
  else {
    // @todo Move this to a fetcher implementation.
    try {
      $response = $this->httpClient->get($form_state->getValue('remote'));
      $data = (string) $response->getBody();
    }
    catch (RequestException $e) {
      $this->logger('aggregator')->warning('Failed to download OPML file due to "%error".', array('%error' => $e->getMessage()));
      drupal_set_message($this->t('Failed to download OPML file due to "%error".', array('%error' => $e->getMessage())));
      return;
    }
  }

  $feeds = $this->parseOpml($data);
  if (empty($feeds)) {
    drupal_set_message($this->t('No new feed has been added.'));
    return;
  }

  // @todo Move this functionality to a processor.
  foreach ($feeds as $feed) {
    // Ensure URL is valid.
    if (!UrlHelper::isValid($feed['url'], TRUE)) {
      drupal_set_message($this->t('The URL %url is invalid.', array('%url' => $feed['url'])), 'warning');
      continue;
    }

    // Check for duplicate titles or URLs.
    $query = $this->feedStorage->getQuery();
    $condition = $query->orConditionGroup()
      ->condition('title', $feed['title'])
      ->condition('url', $feed['url']);
    $ids = $query
    ->condition($condition)
      ->execute();
    $result = $this->feedStorage->loadMultiple($ids);
    foreach ($result as $old) {
      if (strcasecmp($old->label(), $feed['title']) == 0) {
        drupal_set_message($this->t('A feed named %title already exists.', array('%title' => $old->label())), 'warning');
        continue 2;
      }
      if (strcasecmp($old->getUrl(), $feed['url']) == 0) {
        drupal_set_message($this->t('A feed with the URL %url already exists.', array('%url' => $old->getUrl())), 'warning');
        continue 2;
      }
    }

    $new_feed = $this->feedStorage->create(array(
      'title' => $feed['title'],
      'url' => $feed['url'],
      'refresh' => $form_state->getValue('refresh'),
    ));
    $new_feed->save();
  }

  $form_state->setRedirect('aggregator.admin_overview');
}