def asDictionary(self):
        """ returns the data source as a dictionary """
        self._dict = {
            "type": "queryTable",
            "workspaceId": self._workspaceId,
            "query": self._query,
            "oidFields": self._oidFields,
            "spatialReference": {"wkid" : self._wkid}
        }
        if self._geometryType != "":
            self._dict["geometryType"] = self._geometryType
        return self._dict
returns the data source as a dictionary