[3.2.x] Fixed #32687 -- Restored passing process’ environment to underlying tool in dbshell on PostgreSQL.

Regression in bbe6fbb876.

Backport of 6e742dabc9 from main.

django/db/backends/base/client.py

@@ -21,6 +21,5 @@ class BaseDatabaseClient:
 
     def runshell(self, parameters):
         args, env = self.settings_to_cmd_args_env(self.connection.settings_dict, parameters)
-        if env:
-            env = {**os.environ, **env}
+        env = {**os.environ, **env} if env else None
         subprocess.run(args, env=env, check=True)

django/db/backends/postgresql/client.py

@@ -41,7 +41,7 @@ class DatabaseClient(BaseDatabaseClient):
             env['PGSSLCERT'] = str(sslcert)
         if sslkey:
             env['PGSSLKEY'] = str(sslkey)
-        return args, env
+        return args, (env or None)
 
     def runshell(self, parameters):
         sigint_handler = signal.getsignal(signal.SIGINT)

docs/releases/3.2.1.txt

@@ -65,3 +65,6 @@ Bugfixes
   admin changelist now uses ``Exists()`` instead ``QuerySet.distinct()``
   because calling ``delete()`` after ``distinct()`` is not allowed in Django
   3.2 to address a data loss possibility.
+
+* Fixed a regression in Django 3.2 where the calling process environment would
+  not be passed to the ``dbshell`` command on PostgreSQL (:ticket:`32687`).

tests/backends/base/test_client.py

@@ -1,3 +1,5 @@
+from unittest import mock
+
 from django.db import connection
 from django.db.backends.base.client import BaseDatabaseClient
 from django.test import SimpleTestCase
@@ -14,3 +16,15 @@ class SimpleDatabaseClientTests(SimpleTestCase):
         )
         with self.assertRaisesMessage(NotImplementedError, msg):
             self.client.settings_to_cmd_args_env(None, None)
+
+    def test_runshell_use_environ(self):
+        for env in [None, {}]:
+            with self.subTest(env=env):
+                with mock.patch('subprocess.run') as run:
+                    with mock.patch.object(
+                        BaseDatabaseClient,
+                        'settings_to_cmd_args_env',
+                        return_value=([], env),
+                    ):
+                        self.client.runshell(None)
+                    run.assert_called_once_with([], env=None, check=True)

tests/dbshell/test_postgresql.py

@@ -39,7 +39,7 @@ class PostgreSqlDbshellCommandTestCase(SimpleTestCase):
                 'PORT': '444',
             }), (
                 ['psql', '-U', 'someuser', '-h', 'somehost', '-p', '444', 'dbname'],
-                {},
+                None,
             )
         )
 
@@ -100,7 +100,7 @@ class PostgreSqlDbshellCommandTestCase(SimpleTestCase):
     def test_parameters(self):
         self.assertEqual(
             self.settings_to_cmd_args_env({'NAME': 'dbname'}, ['--help']),
-            (['psql', 'dbname', '--help'], {}),
+            (['psql', 'dbname', '--help'], None),
         )
 
     @skipUnless(connection.vendor == 'postgresql', 'Requires a PostgreSQL connection')