public function saveRating($params)
 {
     if (!is_array($params) || count($params) < 1) {
         return false;
     }
     $em = $this->getEntityManager();
     $rating = new Rating();
     $rating->setArticleId($params['article_id']);
     $rating->setStarRating($params['rating']);
     $rating->setCreatedOn(new \DateTime());
     $em->persist($rating);
     $em->flush();
     return true;
 }