def _read_items(self):
        self._items = []
        self._items = glob.glob(path.join(self._config_path, '*.csv'))
        if len(self._items) == 0:
            return 0, -1
        else:
            self._items.sort()
        for i, an_item in enumerate(self._items):
            self._items[i] = an_item.replace(self._config_path + sep, '').replace('.csv', '')
        """ get already loaded playlist id """
        for i, a_playlist in enumerate(self._items):
            if a_playlist ==self._selected_playlist:
                self._selected_playlist_id = i
                break
        self._max_len = len(max(self._items, key=len))
        if self._max_len > 44:
            self._max_len = 44
        self._num_of_items = len(self._items)
get already loaded playlist id