try {
$db_connection = new DbConnection();
$user_repository = new UserDbRepository($db_connection);
$owner = $user_repository->findById($user_id);
if (!$owner) {
throw new UserNotFoundException("Автор с идентификатором \"{$user_id}\" не найден");
}
$article_repository = new ArticleDbRepository($db_connection);
$articles = $article_repository->findByOwnerId($owner->id);
} catch(UserNotFoundException $e) {
// ...
} catch(\Exception $e) {
// ...
}