/**
     * Returns an array of playlist objects that this file is a part of.
     * @return array
     */
    public function getPlaylists()
    {
        $con = Propel::getConnection();
        $sql = <<<SQL
SELECT playlist_id
FROM cc_playlist
WHERE file_id = :file_id
SQL;
        $stmt = $con->prepare($sql);
        $stmt->bindParam(':file_id', $this->id, PDO::PARAM_INT);
        if ($stmt->execute()) {
            $ids = $stmt->fetchAll();
        } else {
            $msg = implode(',', $stmt->errorInfo());
            throw new Exception("Error: {$msg}");
        }
        if (is_array($ids) && count($ids) > 0) {
            return array_map(function ($id) {
                return Application_Model_Playlist::RecallById($id);
            }, $ids);
        } else {
            return array();
        }
    }