Newscoop\Entity\Article::addTopic PHP Method

    public function addTopic(\Newscoop\NewscoopBundle\Entity\Topic $topic)
    {
        if (!$this->topics->contains($topic)) {
            $this->topics->add($topic);
            $topic->addArticleTopic($this);
            return true;
        }
        return false;
    }

 /**
  * Adds topic to the article.
  *
  * @param Topic   $topic   Topic object
  * @param Article $article Article object
  *
  * @return bool
  */
 protected function attachTopicToArticle(Topic $topic, Article $article)
 {
     $result = $article->addTopic($topic);
     if ($result) {
         $this->em->flush();
         $this->dispatcher->dispatch('article-topic.attach', new GenericEvent($this, $this->getLogArray($topic, $article)));
     }
     return $result;
 }