IssueForm::validate PHP Method

    function validate($request)
    {
        if ($temporaryFileId = $this->getData('temporaryFileId')) {
            $user = $request->getUser();
            $temporaryFileDao = DAORegistry::getDAO('TemporaryFileDAO');
            $temporaryFile = $temporaryFileDao->getTemporaryFile($temporaryFileId, $user->getId());
            import('classes.file.PublicFileManager');
            $publicFileManager = new PublicFileManager();
            if (!$publicFileManager->getImageExtension($temporaryFile->getFileType())) {
                $this->addError('coverImage', __('editor.issues.invalidCoverImageFormat'));
            }
        }
        return parent::validate();
    }

 /**
  * Edit the current issue form
  */
 function editIssue($args, $request)
 {
     $issueId = (int) array_shift($args);
     $this->validate($issueId, true);
     $issue =& $this->issue;
     $this->setupTemplate(EDITOR_SECTION_ISSUES);
     $templateMgr =& TemplateManager::getManager();
     $templateMgr->assign('issueId', $issueId);
     $journal =& $request->getJournal();
     $journalId = $journal->getId();
     import('classes.issue.IssueAction');
     $templateMgr->assign('issueOptions', IssueAction::getIssueOptions());
     import('classes.issue.form.IssueForm');
     if (checkPhpVersion('5.0.0')) {
         // WARNING: This form needs $this in constructor
         $issueForm = new IssueForm('editor/issues/issueData.tpl');
     } else {
         $issueForm =& new IssueForm('editor/issues/issueData.tpl');
     }
     $issueForm->readInputData();
     if ($issueForm->validate($issue)) {
         $issueForm->execute($issueId);
         $issueForm->initData($issueId);
     }
     $templateMgr->assign_by_ref('issue', $issue);
     $templateMgr->assign('unpublished', !$issue->getPublished());
     $issueForm->display();
 }