comment_preview

comment_preview(CommentInterface $comment, FormStateInterface $form_state)

function comment_preview(CommentInterface $comment, FormStateInterface $form_state) {
  $preview_build = array();
  $entity = $comment->getCommentedEntity();

  if (!$form_state->getErrors()) {
    $comment->in_preview = TRUE;
    $comment_build = \Drupal::entityTypeManager()->getViewBuilder('comment')->view($comment);
    $comment_build['#weight'] = -100;

    $preview_build['comment_preview'] = $comment_build;
  }

  if ($comment->hasParentComment()) {
    $build = array();
    $parent = $comment->getParentComment();
    if ($parent && $parent->isPublished()) {
      $build = \Drupal::entityTypeManager()->getViewBuilder('comment')->view($parent);
    }
  }
  else {
    // The comment field output includes rendering the parent entity of the
    // thread to which the comment is a reply. The rendered entity output
    // includes the comment reply form, which contains the comment preview and
    // therefore the rendered parent entity. This results in an infinite loop of
    // parent entity output rendering the comment form and the comment form
    // rendering the parent entity. To prevent this infinite loop we temporarily
    // set the value of the comment field on a clone of the entity to hidden
    // before calling entity_view(). That way when the output of the commented
    // entity is rendered, it excludes the comment field output.
    $field_name = $comment->getFieldName();
    $entity = clone $entity;
    $entity->$field_name->status = CommentItemInterface::HIDDEN;
    $build = entity_view($entity, 'full');
  }

  $preview_build['comment_output_below'] = $build;
  $preview_build['comment_output_below']['#weight'] = 100;

  return $preview_build;
}