buildOptionsForm_summary_options example

foreach ($result as $row) {
      $cids[] = $row->cid;
    }

    $this->comments = $this->entityTypeManager->getStorage('comment')->loadMultiple($cids);
  }

  /** * {@inheritdoc} */
  public function buildOptionsForm_summary_options() {
    $options = parent::buildOptionsForm_summary_options();
    $options['title'] = $this->t('Title only');
    $options['default'] = $this->t('Use site default RSS settings');
    return $options;
  }

  public function render($row) {
    global $base_url;

    $cid = $row->{$this->field_alias};
    if (!is_numeric($cid)) {
      return;
    }

  /** * {@inheritdoc} */
  public function buildOptionsForm(&$form, FormStateInterface $form_state) {
    parent::buildOptionsForm($form, $form_state);

    $form['view_mode'] = [
      '#type' => 'select',
      '#title' => $this->t('Display type'),
      '#options' => $this->buildOptionsForm_summary_options(),
      '#default_value' => $this->options['view_mode'],
    ];
  }

  /** * Return the main options, which are shown in the summary title. */
  public function buildOptionsForm_summary_options() {
    $view_modes = $this->entityDisplayRepository->getViewModes($this->entityTypeId);
    $options = [];
    foreach ($view_modes as $mode => $settings) {
      

public $nodes = [];

  /** * {@inheritdoc} */
  protected $entityTypeId = 'node';

  /** * {@inheritdoc} */
  public function buildOptionsForm_summary_options() {
    $options = parent::buildOptionsForm_summary_options();
    $options['title'] = $this->t('Title only');
    $options['default'] = $this->t('Use site default RSS settings');
    return $options;
  }

  public function summaryTitle() {
    $options = $this->buildOptionsForm_summary_options();
    return $options[$this->options['view_mode']];
  }

  public function preRender($values) {