def map_query_string(self):
        """Maps the GET query string params the the query_key_mapper dict and
        updates the request's GET QueryDict with the mapped keys.
        """
        if (not self.query_key_mapper or
            self.request.method == 'POST'):
            # Nothing to map, don't do anything.
            # return self.request.POST
            return {}

        keys = list(self.query_key_mapper.keys())

        return {self.query_key_mapper.get(k) if k in keys else k: v.strip()
                for k, v in self.request.GET.items()}
Maps the GET query string params the the query_key_mapper dict and
        updates the request's GET QueryDict with the mapped keys.