def getall(self):
        try:
            spec = {'data': {'$exists': 1}}
            fields = {'_id': 0}
            sort = [('tid', 1)]
            cur = self.db.docs.find(spec, fields, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        return [Document(**row) for row in cur]
def update_snapshot_metadata_item(self, snapshot_id, id, meta_item):
        """Update metadata item for the snapshot."""
        put_body = json.dumps({'meta': meta_item})
        url = "snapshots/%s/metadata/%s" % (str(snapshot_id), str(id))
        resp, body = self.put(url, put_body)
        body = json.loads(body)
        return resp, body['meta']