[1.8.x] Fixed #14483 -- Allowed using subqueries with GIS lookups

Backport of a0b5f15ea5 from master.

django/contrib/gis/db/models/fields.py

@@ -293,10 +293,11 @@ class GeometryField(GeoSelectFormatMixin, Field):
                              (lookup_type, self.__class__.__name__))
 
     def get_prep_lookup(self, lookup_type, value):
-        if lookup_type == 'isnull':
-            return bool(value)
-        else:
+        if lookup_type == 'contains':
+            # 'contains' name might conflict with the "normal" contains lookup,
+            # for which the value is not prepared, but left as-is.
             return self.get_prep_value(value)
+        return super(GeometryField, self).get_prep_lookup(lookup_type, value)
 
     def get_db_prep_save(self, value, connection):
         "Prepares the value for saving in the database."

django/contrib/gis/db/models/lookups.py

@@ -66,6 +66,9 @@ class GISLookup(Lookup):
 
     def process_rhs(self, compiler, connection):
         rhs, rhs_params = super(GISLookup, self).process_rhs(compiler, connection)
+        if hasattr(self.rhs, '_as_sql'):
+            # If rhs is some QuerySet, don't touch it
+            return rhs, rhs_params
 
         geom = self.rhs
         if isinstance(self.rhs, Col):

django/contrib/gis/tests/geoapp/tests.py

@@ -890,6 +890,21 @@ class GeoQuerySetTest(TestCase):
         self.assertIsNone(qs.unionagg(field_name='point'))
         self.assertIsNone(qs.aggregate(Union('point'))['point__union'])
 
+    def test_within_subquery(self):
+        """
+        Test that using a queryset inside a geo lookup is working (using a subquery)
+        (#14483).
+        """
+        tex_cities = City.objects.filter(
+            point__within=Country.objects.filter(name='Texas').values('mpoly')).order_by('name')
+        expected = ['Dallas', 'Houston']
+        if not connection.features.supports_real_shape_operations:
+            expected.append('Oklahoma City')
+        self.assertEqual(
+            list(tex_cities.values_list('name', flat=True)),
+            expected
+        )
+
     def test_non_concrete_field(self):
         NonConcreteModel.objects.create(point=Point(0, 0), name='name')
         list(NonConcreteModel.objects.all())

django/db/models/sql/compiler.py

@@ -466,7 +466,7 @@ class SQLCompiler(object):
         if obj.low_mark == 0 and obj.high_mark is None and not self.query.distinct_fields:
             # If there is no slicing in use, then we can safely drop all ordering
             obj.clear_ordering(True)
-        return obj.get_compiler(connection=self.connection).as_sql()
+        return obj.get_compiler(connection=self.connection).as_sql(subquery=True)
 
     def get_default_columns(self, start_alias=None, opts=None, from_parent=None):
         """

docs/releases/1.8.txt

@@ -216,6 +216,9 @@ Minor features
 * A new :doc:`GeoJSON serializer </ref/contrib/gis/serializers>` is now
   available.
 
+* It is now allowed to include a subquery as a geographic lookup argument, for
+  example ``City.objects.filter(point__within=Country.objects.filter(continent='Africa').values('mpoly'))``.
+
 * The Spatialite backend now supports ``Collect`` and ``Extent`` aggregates
   when the database version is 3.0 or later.