(We are in a QuerySet, self = Trips.object)

        ogr_departure = smart_transform(departure_point,SRID_TRANSFORM, from_srid=SRID_DEFAULT).ogr
        ogr_arrival = smart_transform(arrival_point,SRID_TRANSFORM, from_srid=SRID_DEFAULT).ogr
        offers = self.filter(offer__isnull=False)
        offers = offers.select_related('user', 'offer')

            off = offers.extra(
            select=SortedDict([
                ('pourcentage_rank', """get_pourcentage_rank(
                    "carpool_tripoffer"."direction_route_proj",
                    ST_PointFromWKB(ST_AsEWKB('%s'::geometry)),
                    ST_PointFromWKB(ST_AsEWKB('%s'::geometry))
                )
                """),
            ]),
            select_params=(
                ogr_departure.wkt,
                ogr_arrival.wkt,
            ),
            where=[
                """ST_DWithin(
                    "carpool_tripoffer"."simple_route_proj",
                    ST_PointFromWKB(ST_AsEWKB('%s'::geometry)),
                    "carpool_tripoffer"."radius" + %s
                )
                """,
                """ST_DWithin(
                    "carpool_tripoffer"."simple_route_proj",
                    ST_PointFromWKB(ST_AsEWKB('%s'::geometry)),
                    "carpool_tripoffer"."radius" + %s
                )
                """,
                """get_pourcentage_rank(
                    "carpool_tripoffer"."direction_route_proj",
                    ST_PointFromWKB(ST_AsEWKB('%s'::geometry)),
                    ST_PointFromWKB(ST_AsEWKB('%s'::geometry))
                ) >= %s
                """,
            ],
            params=[
                ogr_departure.wkt, radius,
                ogr_arrival.wkt, radius,
                ogr_departure.wkt,
                ogr_arrival.wkt,
                self.MAX_PERCENTAGE_RANK,
            ]
        )
        return off