public function create(User $user, $title, $url, $tag)
{
if ($errors = $this->getErrors($title, $url, $tag)) {
throw new ServiceException($errors);
}
$post = new Post();
$post->setUser($user);
$post->setTitle($title);
$post->setUrl($url);
$post->setTag($this->formatTag($tag));
$post->setUpvoteTotal(0);
$post->setCreatedAt(new \DateTime());
return $this->repository->create($post);
}