OphCoTherapyapplication_FileCollection::getZipFile PHP Method

    public function getZipFile()
    {
        if (!$this->compressed_file) {
            // need to generate zip file, and store it with this collection
            $pfile = ProtectedFile::createForWriting($this->name . '.zip');
            $zip = new ZipArchive();
            if (!$zip->open($pfile->getPath(), ZIPARCHIVE::OVERWRITE)) {
                throw new Exception('cannot create zip file');
            }
            foreach ($this->files as $pf) {
                $zip->addFile($pf->getPath(), $pf->name);
            }
            $zip->close();
            $pfile->save();
            // set up relation
            $this->compressed_file = $pfile;
            $this->zipfile_id = $pfile->id;
            $this->save();
        }
        return $this->compressed_file;
    }