From efcc0f25a77120f728379a594af3e256e771b7f8 Mon Sep 17 00:00:00 2001
From: Stefan Brand <stefan.brand@eox.at>
Date: Fri, 17 Feb 2023 09:44:17 +0100
Subject: [PATCH] [4.2.x] Fixed #34302 -- Fixed SpatialReference.srid for
 objects without top-level authority.

Backport of eacf6b73d8eace004f840bd9b80c8c671caab9da from main
---
 django/contrib/gis/gdal/srs.py         |  2 +-
 tests/gis_tests/gdal_tests/test_srs.py | 12 +++++++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/django/contrib/gis/gdal/srs.py b/django/contrib/gis/gdal/srs.py
index 4df44190264..50fc41c1fda 100644
--- a/django/contrib/gis/gdal/srs.py
+++ b/django/contrib/gis/gdal/srs.py
@@ -208,7 +208,7 @@ class SpatialReference(GDALBase):
     def srid(self):
         "Return the SRID of top-level authority, or None if undefined."
         try:
-            return int(self.attr_value("AUTHORITY", 1))
+            return int(self.auth_code(target=None))
         except (TypeError, ValueError):
             return None
 
diff --git a/tests/gis_tests/gdal_tests/test_srs.py b/tests/gis_tests/gdal_tests/test_srs.py
index 293144aa8e5..9bfe5680dab 100644
--- a/tests/gis_tests/gdal_tests/test_srs.py
+++ b/tests/gis_tests/gdal_tests/test_srs.py
@@ -102,7 +102,10 @@ srlist = (
         ang_name="Degree",
         lin_units=0.3048006096012192,
         ang_units=0.0174532925199,
-        auth={"PROJCS": (None, None)},
+        auth={
+            None: (None, None),  # Top-level authority.
+            "PROJCS": (None, None),
+        },
         attr=(
             ("PROJCS|GeOgCs|spheroid", "GRS 1980"),
             (("projcs", 9), "UNIT"),
@@ -391,3 +394,10 @@ class SpatialRefTest(SimpleTestCase):
         self.assertIn('DATUM["D_North_American_1983"', srs.wkt)
         srs.from_esri()
         self.assertIn('DATUM["North_American_Datum_1983"', srs.wkt)
+
+    def test_srid(self):
+        """The srid property returns top-level authority code."""
+        for s in srlist:
+            if hasattr(s, "epsg"):
+                srs = SpatialReference(s.wkt)
+                self.assertEqual(srs.srid, s.epsg)