notifications: Fix setting last_update_time

The field last_update_time is set to auto_now in the Django model, but it is not
being updated when using update_or_create() since Django 4.2. This is because it
sends update_fields= argument to save().

Say, a user installed an app a few hours ago and uninstalls it now, the
notification should be updated to show the uninstallation status but it shows
the timestamp of the installation instead.

Explicitly setting the updated timestamp is one way of fixing this issue.

Signed-off-by: Joseph Nuthalapati <njoseph@riseup.net>
[sunil: Use django_db mark in test case]
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>

plinth/notification.py

@@ -8,6 +8,7 @@ from django.core.exceptions import ValidationError
 from django.db.models import Q
 from django.template.exceptions import TemplateDoesNotExist
 from django.template.response import SimpleTemplateResponse
+from django.utils import timezone
 from django.utils.translation import gettext
 
 from plinth import cfg
@@ -229,9 +230,11 @@ class Notification(models.StoredNotification):
 
         """
         id = kwargs.pop('id')
+        fields_to_update = kwargs.copy()
+        fields_to_update['last_update_time'] = timezone.now()
         with db.lock:
             return Notification.objects.update_or_create(
-                defaults=kwargs, id=id)[0]
+                defaults=fields_to_update, id=id)[0]
 
     @staticmethod
     def get(key):  # pylint: disable=redefined-builtin

plinth/tests/test_notification.py

@@ -413,3 +413,28 @@ def test_display_context_body_template(note, user, load_cfg, rf):
     context_note = context['notifications'][0]
     assert context_note['body'].content == \
         b'Test notification body /plinth/help/about/\n'
+
+
+@pytest.mark.django_db
+def test_last_update_time_updates_on_modify():
+    """Test that last_update_time is updated on modify via update_or_create."""
+    # Given a notification is created at time t1
+    t1 = datetime.datetime(2025, 1, 1, tzinfo=datetime.timezone.utc)
+    with patch('django.utils.timezone.now', return_value=t1):
+        Notification.update_or_create(id='timestamp-test', app_id='app',
+                                      severity='info', title='Title')
+
+    first_note = Notification.get('timestamp-test')
+    assert first_note.last_update_time == t1
+
+    # When the same notification is updated at later time t2
+    t2 = t1 + datetime.timedelta(minutes=5)
+    with patch('django.utils.timezone.now', return_value=t2):
+        Notification.update_or_create(id='timestamp-test', app_id='app',
+                                      severity='warning', title='Title2')
+
+    second_note = Notification.get('timestamp-test')
+
+    # Then the last_update_time should be t2
+    assert second_note.last_update_time == t2
+    assert second_note.last_update_time > first_note.last_update_time