Fixed #29955 -- Added support for distance expression to the dwithin lookup.

This was missed when adding support to other distance lookups in
refs #25499.

Thanks Peter Bex for the report and Mariusz for testcases.

2 files changed, 25 insertions, 0 deletions

diff --git a/tests/gis_tests/distapp/models.py b/tests/gis_tests/distapp/models.py
index fcad6fc097..1971741c54 100644
--- a/tests/gis_tests/distapp/models.py
+++ b/tests/gis_tests/distapp/models.py
@@ -28,6 +28,7 @@ class AustraliaCity(NamedModel):
     "City model for Australia, using WGS84."
     point = models.PointField()
     radius = models.IntegerField(default=10000)
+    allowed_distance = models.FloatField(default=0.5)
 
 
 class CensusZipcode(NamedModel):
diff --git a/tests/gis_tests/distapp/tests.py b/tests/gis_tests/distapp/tests.py
index d84e829868..2cdd0e8f0e 100644
--- a/tests/gis_tests/distapp/tests.py
+++ b/tests/gis_tests/distapp/tests.py
@@ -234,6 +234,30 @@ class DistanceTest(TestCase):
         ).filter(annotated_value=True)
         self.assertEqual(self.get_names(qs), ['77002', '77025', '77401'])
 
+    @skipUnlessDBFeature('supports_dwithin_lookup', 'supports_dwithin_distance_expr')
+    def test_dwithin_with_expression_rhs(self):
+        # LineString of Wollongong and Adelaide coords.
+        ls = LineString(((150.902, -34.4245), (138.6, -34.9258)), srid=4326)
+        qs = AustraliaCity.objects.filter(
+            point__dwithin=(ls, F('allowed_distance')),
+        ).order_by('name')
+        self.assertEqual(
+            self.get_names(qs),
+            ['Adelaide', 'Mittagong', 'Shellharbour', 'Thirroul', 'Wollongong'],
+        )
+
+    @skipIfDBFeature('supports_dwithin_distance_expr')
+    def test_dwithin_with_expression_rhs_not_supported(self):
+        ls = LineString(((150.902, -34.4245), (138.6, -34.9258)), srid=4326)
+        msg = (
+            'This backend does not support expressions for specifying '
+            'distance in the dwithin lookup.'
+        )
+        with self.assertRaisesMessage(NotSupportedError, msg):
+            list(AustraliaCity.objects.filter(
+                point__dwithin=(ls, F('allowed_distance')),
+            ))
+
 
 '''
 =============================