def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def __init__(self, backendsdialog):
        """
        Constructor, just initializes the gtk widgets

        @param backends: a reference to the dialog in which this is
        loaded
        """
        super().__init__()
        self.dialog = backendsdialog
        self.req = backendsdialog.get_requester()
        self._init_liststore()
        self._init_renderers()
        self._init_signals()
        self.refresh()