Fixed #24894 -- Added contrib.postgres.functions.TransactionNow

tests/postgres_tests/migrations/0002_create_test_models.py

@@ -130,6 +130,13 @@ class Migration(migrations.Migration):
                 ('related_field', models.ForeignKey('postgres_tests.AggregateTestModel', null=True)),
             ]
         ),
+        migrations.CreateModel(
+            name='NowTestModel',
+            fields=[
+                ('id', models.AutoField(verbose_name='ID', serialize=False, auto_created=True, primary_key=True)),
+                ('when', models.DateTimeField(null=True, default=None)),
+            ]
+        ),
     ]
 
     pg_92_operations = [

tests/postgres_tests/models.py

@@ -109,3 +109,7 @@ class StatTestModel(models.Model):
     int1 = models.IntegerField()
     int2 = models.IntegerField()
     related_field = models.ForeignKey(AggregateTestModel, null=True)
+
+
+class NowTestModel(models.Model):
+    when = models.DateTimeField(null=True, default=None)

tests/postgres_tests/test_functions.py

@@ -0,0 +1,28 @@
+from datetime import datetime
+from time import sleep
+
+from django.contrib.postgres.functions import TransactionNow
+
+from . import PostgreSQLTestCase
+from .models import NowTestModel
+
+
+class TestTransactionNow(PostgreSQLTestCase):
+
+    def test_transaction_now(self):
+        """
+        The test case puts everything under a transaction, so two models
+        updated with a short gap should have the same time.
+        """
+        m1 = NowTestModel.objects.create()
+        m2 = NowTestModel.objects.create()
+
+        NowTestModel.objects.filter(id=m1.id).update(when=TransactionNow())
+        sleep(0.1)
+        NowTestModel.objects.filter(id=m2.id).update(when=TransactionNow())
+
+        m1.refresh_from_db()
+        m2.refresh_from_db()
+
+        self.assertIsInstance(m1.when, datetime)
+        self.assertEqual(m1.when, m2.when)