$article = $articlesModel->find($id);
$file = $article->getAttachement($filesModel, $name);
$files = $article->getAttachement($filesModel);

public function getAttachement($filesModel, $name = NULL)
{
    if ($name) {
        return $filesModel->find($this->id, $name);
    } else {
        return $fileSModel->findAll($this->id);
    }
}