public function getTags($blog, array $postData = [])
    {
        $postUuids = array_column($postData, 'id');

        $event = new GenericDataEvent([
            'class' => 'Icap\BlogBundle\Entity\Post',
            'ids' => $postUuids,
            'frequency' => true,
        ]);

        $this->eventDispatcher->dispatch(
            'claroline_retrieve_used_tags_by_class_and_ids',
            $event
        );
        $tags = $event->getResponse();

        //only keep max tag number, if defined
        if ($blog->getOptions()->isTagTopMode() && $blog->getOptions()->getMaxTag() > 0) {
            arsort($tags);
            $tags = array_slice($tags, 0, $blog->getOptions()->getMaxTag());
        }

        return (object) $tags;
    }