Source code for django.contrib.gis.db.models.manager
from django.contrib.gis.db.models.query import GeoQuerySet
from django.db.models.manager import Manager
class GeoManager(Manager.from_queryset(GeoQuerySet)):
"Overrides Manager to return Geographic QuerySets."
# This manager should be used for queries on related fields
# so that geometry columns on Oracle and MySQL are selected
# properly.
use_for_related_fields = True