feat(django-spanner)!: support Django 5.2 and deprecate Django 3.2/4.2 by sinhasubham · Pull Request #16624 · googleapis/google-cloud-python

sinhasubham · 2026-04-13T09:07:38Z

This PR migrates the django-google-spanner package to support Django 5.2 and deprecates support for older Django versions (3.2 and 4.2). Due to the deprecation of older versions, this is a breaking change and requires a major version release.
💥 BREAKING CHANGES:

Dropped support for Django 3.2 and 4.2.
Minimum supported Python version is now 3.10 (as required by Django 5.2).

gemini-code-assist

Code Review

This pull request updates the Spanner database backend to support Django 5.2 and Python 3.10+, while removing legacy support for Django 3.2 and 4.2. Key changes include the implementation of a global client cache to prevent initialization crashes, support for JSONArray, GeneratedField, and db_default, and a retry mechanism for flushing tables with foreign key constraints. Feedback highlights several critical issues: the use of a 32-bit mask for primary key generation significantly reduces the key space, and making GOOGLE_CLOUD_PROJECT mandatory is a breaking change for local development. Additionally, the package version was incorrectly decremented, and a minor version bump was recommended for this release. Finally, using WHERE 1=1 was suggested as a more idiomatic alternative to WHERE true for flush operations.

…bsolete workflows

surbhigarg92 · 2026-04-20T07:07:21Z


+# Global cache for Spanner client to prevent multiple initializations
+# which can cause OpenTelemetry 'MeterProvider override' crashes.
+_SPANNER_CLIENT_CACHE = None


I dont understand why do we need this, ideally our Spanner client library should handle the override crash ?

Added this global cache to fix a crash observed during testing: OpenTelemetry MeterProvider override crashes. In Django, DatabaseWrapper instances are created frequently (e.g., per thread or request), leading to multiple spanner.Client initializations. While it would be ideal for the client library to handle this, this cache effectively prevents the crash and resource exhaustion in the meantime.

Got it. Please create a bug in Python Spanner Client and add a todo here to clean this up once the bug is fixed

surbhigarg92 · 2026-04-20T07:09:46Z

+            "project": os.environ.get("GOOGLE_CLOUD_PROJECT")
+            or self.settings_dict.get("project")
+            or self.settings_dict.get("PROJECT")
+            or "test-project",


This is being done in multiple places, better to extract in "init" method once and use it everywhere.

Also why do we support self.settings_dict.get("project") and self.settings_dict.get("PROJECT") now ?

Addressed. I made these changes for some debugging purpose earlier, missed to revert in the final commit.

surbhigarg92 · 2026-04-20T07:30:17Z

+        conn_params.pop("instance", None)
+        conn_params.pop("instance_id", None)
+        conn_params.pop("client", None)


Why this change is required ?
We are not using instance_id or client anywhere. We are only using instance.instance_id or instance._client

Because get_connection_params puts instance_id into the conn_params dictionary by default, passing **conn_params will try to pass instance_id again. Python rejects this because it is receiving the same argument twice.
Popping instance_id and client from conn_params is required to support the global client cache fix. Removing this crashes the adapter on connection.

surbhigarg92 · 2026-04-20T08:13:21Z

+        # This method copies the complete code of this overridden method from
+        # Django core and modify it for Spanner by adding one line


This is duplicate comment

surbhigarg92 · 2026-04-20T08:23:54Z

 # https://developers.google.com/open-source/licenses/bsd

-__version__ = "4.0.3"
+__version__ = "4.1.0"


Why are we modifying this version manually ? shouldn't this be updated automatically once we do the release ?

Makes sense, addressed

surbhigarg92 · 2026-04-20T08:27:50Z

        self.assertEqual(
            sql_compiled,
-            "SELECT tests_report.name FROM tests_report ORDER BY "
+            "SELECT tests_report.name AS name FROM tests_report ORDER BY "


For my knowledge why this change is required ?

surbhigarg92 · 2026-04-20T08:32:12Z


 UNIT_TEST_PYTHON_VERSIONS = [
-    "3.8",
    "3.9",


I thought we received 3.9 support as well, as we removed 3.9 integration test suite file

The unit 3.9 workflow step fails without version 3.9 in this list. And we cannot remove 3.9 from github workflows as it is a common workflow file for monorepo now. I will check on this with owning team how we are planning to handle this

surbhigarg92 · 2026-04-20T08:32:53Z

+    if session.python == "3.9":
+        session.skip("Python 3.9 is not supported for Django 5.2 tests")


Lets remove 3.9 from the list then ?

Since unittest.yml is a shared github workflow for all packages in the monorepo, I cannot remove Python 3.9 from it without affecting other libraries.

surbhigarg92 · 2026-04-20T08:35:21Z

 # https://developers.google.com/open-source/licenses/bsd

-__version__ = "4.0.3"
+__version__ = "4.1.0"


Also this should go as a Major version release, since we are deprecating older vesion of Django.

PR title should be feat! to trigger a major version

Sure, will update the PR title

sakthivelmanii · 2026-04-20T06:04:44Z

-from django.db import DEFAULT_DB_ALIAS
-from django.db.models.fields import (
+
+from django.db import DEFAULT_DB_ALIAS  # noqa: E402


why are you suppressing linting errors?

sakthivelmanii · 2026-04-20T06:06:28Z


 def gen_rand_int64():
    # Credit to https://stackoverflow.com/a/3530326.
+    # Use 32-bit integer for Emulator compatibility (High-bit issues observed).


Is this a valid comment?

I had removed the 32-bit integer changes here but missed to remove this comment earlier. Removed now

sakthivelmanii · 2026-04-20T06:07:55Z

-                    method_name,
-                    skip("unsupported by Spanner")(method),
-                )
+                try:


Make you sure you clean up the method. Not suppress the error.

Since we need to support a range of Django versions, a test that is non-existent in 5.2 might still need to be skipped in 4.2. Suppressing the AttributeError is the best way to handle this scenario in long term according to me.

sakthivelmanii · 2026-04-20T06:09:42Z

            "constraint": self.sql_check_constraint % {"check": check},
        }

-    def _unique_sql(


why are we removing it?

The method was initially removed in an attempt to rely on the Django 5.2 base class implementation. But i agree, the custom implementation is required to prevent Django from generating inline UNIQUE constraints in CREATE TABLE statements, which base class implementation does not support in the same way. I have restored the method and updated it to support Django 5.2's nulls_distinct feature.

sakthivelmanii · 2026-04-20T08:36:49Z

@@ -28,7 +28,6 @@
 DEFAULT_PYTHON_VERSION = "3.14"

 UNIT_TEST_PYTHON_VERSIONS = [


Remove support for 3.8 and 3.9

The unit 3.9 workflow step fails without version 3.9 in this list. And we cannot remove 3.9 from github workflows as it is a common workflow file for monorepo now. I will check on this with owning team how we are planning to handle this

sakthivelmanii · 2026-04-20T08:38:21Z

        else:
            return []

+    def execute_sql_flush(self, sql_list):


this looks so bruteforce. is there any other better approach?

Earlier, we were relying on Django's default execute_sql_flush, which fails on Spanner when foreign key constraints are present. This retry logic was introduced in this PR specifically to handle Spanner's inability to disable foreign key checks during test cleanup.
I agree that the retry loop in execute_sql_flush is a brute-force approach. But to avoid the complexity of implementing a full topological sort of the tables based on their foreign key dependencies to determine the exact deletion order (child tables first, then parents), i used this multi-pass approach.

sakthivelmanii · 2026-04-20T08:40:05Z

    # Spanner does not support expression indexes
    # example: CREATE INDEX index_name ON table (LOWER(column_name))
    supports_expression_indexes = False
+    supports_stored_generated_columns = True

    # Django tests that aren't supported by Spanner.
    skip_tests = (


We need to group them by cause. Otherwise we will not know if we are doing it correctly or not.

surbhigarg92 · 2026-04-20T08:44:07Z

+                        try:
+                            cursor.execute(sql)
+                            progress = True
+                        except Exception as e:


catch more specific exception ?

Spanner might raise various errors (such as Aborted, FailedPrecondition, or IntegrityError) depending on which constraint is violated first. I felt adding generic exception catching was better in this case instead of maintaining list of exceptions for same block.

…d tests

sinhasubham changed the title ~~Django upgrade 5 2~~ feat: migrate Django 5.2 upgrade and 3.2/4.2 deprecations Apr 13, 2026

gemini-code-assist Bot reviewed Apr 13, 2026

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sinhasubham added 2 commits April 14, 2026 22:29

feat: migrate Django 5.2 upgrade and 3.2/4.2 deprecations

d1ae45b

feat(django-spanner): Stabilize system tests for Django 5.2 migration

c54a68d

sinhasubham force-pushed the django_upgrade_5_2 branch 4 times, most recently from 2b71c2a to f6098f1 Compare April 16, 2026 09:17

chore(django-spanner): stabilize Django 5.2 system tests and remove o…

4fc923b

…bsolete workflows

sinhasubham force-pushed the django_upgrade_5_2 branch from f6098f1 to 4fc923b Compare April 16, 2026 10:03

sinhasubham requested a review from surbhigarg92 April 20, 2026 05:57

sinhasubham marked this pull request as ready for review April 20, 2026 05:57

sinhasubham requested review from a team as code owners April 20, 2026 05:57

surbhigarg92 reviewed Apr 20, 2026

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Comment thread packages/django-google-spanner/django_spanner/creation.py

surbhigarg92 reviewed Apr 20, 2026

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sakthivelmanii reviewed Apr 20, 2026

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surbhigarg92 reviewed Apr 20, 2026

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surbhigarg92 requested changes Apr 20, 2026

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parthea mentioned this pull request Apr 21, 2026

chore: complete migration of django-google-spanner to librarian #16748

Draft

chore(django-spanner): address PR review feedback and organize skippe…

941fe99

…d tests

sinhasubham force-pushed the django_upgrade_5_2 branch from 01d798c to 941fe99 Compare April 23, 2026 11:59

sinhasubham changed the title ~~feat: migrate Django 5.2 upgrade and 3.2/4.2 deprecations~~ feat!: migrate Django 5.2 upgrade and 3.2/4.2 deprecations Apr 23, 2026

sinhasubham changed the title ~~feat!: migrate Django 5.2 upgrade and 3.2/4.2 deprecations~~ feat(django-spanner)!: support Django 5.2 and deprecate Django 3.2/4.2 Apr 23, 2026

surbhigarg92 approved these changes Apr 23, 2026

View reviewed changes

		# This method copies the complete code of this overridden method from
		# Django core and modify it for Spanner by adding one line

		if session.python == "3.9":
		session.skip("Python 3.9 is not supported for Django 5.2 tests")

		@@ -28,7 +28,6 @@
		DEFAULT_PYTHON_VERSION = "3.14"

		UNIT_TEST_PYTHON_VERSIONS = [

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sinhasubham Apr 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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sinhasubham commented Apr 13, 2026 •

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