class Rss

class Rss extends RssPluginBase {
    
    /**
     * {@inheritdoc}
     */
    protected $base_table = 'comment_field_data';
    
    /**
     * {@inheritdoc}
     */
    protected $base_field = 'cid';
    
    /**
     * @var \Drupal\comment\CommentInterface[]
     */
    protected $comments;
    
    /**
     * {@inheritdoc}
     */
    protected $entityTypeId = 'comment';
    public function preRender($result) {
        $cids = [];
        foreach ($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;
        }
        $view_mode = $this->options['view_mode'];
        if ($view_mode == 'default') {
            $view_mode = \Drupal::config('system.rss')->get('items.view_mode');
        }
        // Load the specified comment and its associated node:
        
        /** @var $comment \Drupal\comment\CommentInterface */
        $comment = $this->comments[$cid];
        if (empty($comment)) {
            return;
        }
        $comment->link = $comment->toUrl('canonical', [
            'absolute' => TRUE,
        ])
            ->toString();
        $comment->rss_namespaces = [];
        $comment->rss_elements = [
            [
                'key' => 'pubDate',
                'value' => gmdate('r', $comment->getCreatedTime()),
            ],
            [
                'key' => 'dc:creator',
                'value' => $comment->getAuthorName(),
            ],
            [
                'key' => 'guid',
                'value' => 'comment ' . $comment->id() . ' at ' . $base_url,
                'attributes' => [
                    'isPermaLink' => 'false',
                ],
            ],
        ];
        // The comment gets built and modules add to or modify
        // $comment->rss_elements and $comment->rss_namespaces.
        $build = $this->entityTypeManager
            ->getViewBuilder('comment')
            ->view($comment, 'rss');
        unset($build['#theme']);
        if (!empty($comment->rss_namespaces)) {
            $this->view->style_plugin->namespaces = array_merge($this->view->style_plugin->namespaces, $comment->rss_namespaces);
        }
        $item = new \stdClass();
        if ($view_mode != 'title') {
            // We render comment contents.
            $item->description = $build;
        }
        $item->title = $comment->label();
        $item->link = $comment->link;
        // Provide a reference so that the render call in
        // template_preprocess_views_view_row_rss() can still access it.
        $item->elements =& $comment->rss_elements;
        $item->cid = $comment->id();
        $build = [
            '#theme' => $this->themeFunctions(),
            '#view' => $this->view,
            '#options' => $this->options,
            '#row' => $item,
        ];
        return $build;
    }

}