Fixed #27573 -- Made Distance on geodetic coordinates return a raw va…

…lue on MySQL.

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

@@ -253,15 +253,13 @@ def source_is_geography(self):
     def convert_value(self, value, expression, connection, context):
         if value is None:
             return None
+        dist_att = None
         geo_field = self.geo_field
         if geo_field.geodetic(connection):
-            dist_att = 'm'
+            if connection.features.supports_distance_geodetic:
+                dist_att = 'm'
         else:
-            units = geo_field.units_name(connection)
-            if units:
-                dist_att = DistanceMeasure.unit_attname(units)
-            else:
-                dist_att = None
+            dist_att = geo_field.units_name(connection)
         if dist_att:
             return DistanceMeasure(**{dist_att: value})
         return value

tests/gis_tests/distapp/tests.py

@@ -5,7 +5,7 @@
 from django.contrib.gis.measure import D  # alias for Distance
 from django.db import connection
 from django.db.models import F, Q
-from django.test import TestCase, skipUnlessDBFeature
+from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
 
 from ..utils import no_oracle, oracle, postgis, spatialite
 from .models import (
@@ -360,6 +360,14 @@ def test_distance_geodetic_spheroid(self):
             for i, c in enumerate(qs):
                 self.assertAlmostEqual(sphere_distances[i], c.distance.m, tol)
 
+    @skipIfDBFeature("supports_distance_geodetic")
+    @skipUnlessDBFeature("has_Distance_function")
+    def test_distance_function_raw_result(self):
+        distance = Interstate.objects.annotate(
+            d=Distance(Point(0, 0, srid=4326), Point(0, 1, srid=4326)),
+        ).first().d
+        self.assertEqual(distance, 1)
+
     @no_oracle  # Oracle already handles geographic distance calculation.
     @skipUnlessDBFeature("has_Distance_function", 'has_Transform_function')
     def test_distance_transform(self):