Symfony2: Inserting a collection of files - php

Question

While trying to insert a collection of entities which have a file field, i couldn't figure out if there's is a better way to create the UploadedFile Object being cast by the Document::document annotation. Here's my code, any help on improving it is very appreciated :)
public function createAction(Request $request) {
$em = $this->getDoctrine()->getManager();
$user = $this->get('security.context')->getToken()->getUser();
$entity = new Paper();
$form = $this->createCreateForm($entity);
$form->handleRequest($request);
if ($form->isValid()) {
$entity->setAuthor($user);
$em->persist($entity);
// chotest foreach in the universe
if (isset($_FILES) && array_key_exists('arkad1a_cfpbundle_paper', $_FILES)) {
foreach ($_FILES['arkad1a_cfpbundle_paper']['name']['documents'] as $k => $v) {
$document = new UploadedFile(
$_FILES['arkad1a_cfpbundle_paper']['tmp_name']['documents'][$k]['document'],
$_FILES['arkad1a_cfpbundle_paper']['name']['documents'][$k]['document'],
$_FILES['arkad1a_cfpbundle_paper']['type']['documents'][$k]['document'],
$_FILES['arkad1a_cfpbundle_paper']['size']['documents'][$k]['document'],
$_FILES['arkad1a_cfpbundle_paper']['error']['documents'][$k]['document'],
false
);
$Document = new \Arkad1a\CFPBundle\Entity\Document();
$Document->setAuthor($user)
->setDocument($document)
->setPaper($entity)
->upload();
$em->persist($Document);
}
}
$em->flush();
return $this->redirect($this->generateUrl('paper_show', array('id' => $entity->getId())));
} else {
die('invalid');
}
return array(
'entity' => $entity,
'form' => $form->createView(),
);
}