Fixed #26775 -- Supported dim=3 geography fields

Thanks François-Xavier Thomas for the report.

django/contrib/gis/db/backends/postgis/operations.py

@@ -268,18 +268,19 @@ class PostGISOperations(BaseSpatialOperations, DatabaseOperations):
         """
         if f.geom_type == 'RASTER':
             return 'raster'
-        elif f.geography:
-            if f.srid != 4326:
-                raise NotImplementedError('PostGIS only supports geography columns with an SRID of 4326.')
 
-            return 'geography(%s,%d)' % (f.geom_type, f.srid)
-        else:
         # Type-based geometries.
         # TODO: Support 'M' extension.
         if f.dim == 3:
             geom_type = f.geom_type + 'Z'
         else:
             geom_type = f.geom_type
+        if f.geography:
+            if f.srid != 4326:
+                raise NotImplementedError('PostGIS only supports geography columns with an SRID of 4326.')
+
+            return 'geography(%s,%d)' % (geom_type, f.srid)
+        else:
             return 'geometry(%s,%d)' % (geom_type, f.srid)
 
     def get_distance(self, f, dist_val, lookup_type, handle_spheroid=True):

tests/gis_tests/geo3d/models.py

@@ -19,6 +19,7 @@ class NamedModel(models.Model):
 
 class City3D(NamedModel):
     point = models.PointField(dim=3)
+    pointg = models.PointField(dim=3, geography=True)
 
 
 class Interstate2D(NamedModel):

tests/gis_tests/geo3d/tests.py

@@ -85,7 +85,9 @@ class Geo3DLoadingHelper(object):
 
     def _load_city_data(self):
         for name, pnt_data in city_data:
-            City3D.objects.create(name=name, point=Point(*pnt_data, srid=4326))
+            City3D.objects.create(
+                name=name, point=Point(*pnt_data, srid=4326), pointg=Point(*pnt_data, srid=4326),
+            )
 
     def _load_polygon_data(self):
         bbox_wkt, bbox_z = bbox_data
@@ -122,9 +124,11 @@ class Geo3DTest(Geo3DLoadingHelper, TestCase):
         self._load_city_data()
         for name, pnt_data in city_data:
             city = City3D.objects.get(name=name)
-            z = pnt_data[2]
+            # Testing both geometry and geography fields
             self.assertTrue(city.point.hasz)
-            self.assertEqual(z, city.point.z)
+            self.assertTrue(city.pointg.hasz)
+            self.assertEqual(city.point.z, pnt_data[2])
+            self.assertEqual(city.pointg.z, pnt_data[2])
 
     def test_3d_polygons(self):
         """