gistfile1.php

  protected function processForm(sfWebRequest $request, sfForm $form)
  {
    $form->bind($request->getParameter($form->getName()), $request->getFiles($form->getName()));
    if ($form->isValid())
    {
      $file = $form->getValue('file');
      if($file)
      {
        $ad->setMimeType($form->getValue('file')->getType());
      }

      $ad = $form->save();

      $this->redirect('ads/edit?id='.$ad->getId());
    }
  }