GeoDjango ORM查找错误地将几何转换为SQL中不需要的SRID

Question

In the query below lookup with geometry variable wrongly transforms geometry to unwanted SRID in SQL.

Buildings.objects.annotate(
    area_krovak=Transform('area', self.KROVAK_SRID), 
    intersection_area=RawSQL('ST_Area(ST_Intersection(ST_Transform(area, {krovak}), ST_GeomFromEWKB(\'\\x{district_geom}\')))'.format(district_geom=geometry.ewkb.hex(), krovak=5514), [])
).filter(area_krovak__intersects=geometry)

Building.area is in db a MultipolygonField() , in db there is by default SRID 4326 (WGS84). geometry is GEOSGeometry in Krovak projection (SRID 5514). To make ST_Intersection work I need both in the same projection, so I added the field area_krovak in the corresponding projection. But the =geometry part in lookup area_krovak__intersects=geometry results in the following SQL (when I print .query )

ST_Transform(ST_GeomFromEWKB('blabla'::bytea), 4326)

For some reason Django transforms it to 4326 and therefore it does not work.

Answer 1

Buildings.objects.annotate(
    area_krovak=Transform('area', self.KROVAK_SRID, output_field=MultiPolygonField(srid=5514)), 
    intersection_area=RawSQL('ST_Area(ST_Intersection(ST_Transform(area, {krovak}), ST_GeomFromEWKB(\'\\x{district_geom}\')))'.format(district_geom=geometry.ewkb.hex(), krovak=5514), [])
).filter(area_krovak__intersects=geometry)

Adding output_field with appropriate SRID just solved it