update instance date_modified when deleting instance

onadata/libs/tests/utils/test_logger_tools.py

@@ -1084,7 +1084,7 @@ def test_hard_delete_subset(self):
         self.assertEqual(self.xform.num_of_submissions, 3)
 
     def test_sets_deleted_at(self):
-        """Deleted_at is set to the current time"""
+        """deleted_at is set to the current time"""
         mocked_now = timezone.now()
 
         with patch("django.utils.timezone.now", Mock(return_value=mocked_now)):
@@ -1094,6 +1094,17 @@ def test_sets_deleted_at(self):
             all(instance.deleted_at == mocked_now for instance in self.instances)
         )
 
+    def test_sets_date_modified(self):
+        """date_modified is set to the current time"""
+        mocked_now = timezone.now()
+
+        with patch("django.utils.timezone.now", Mock(return_value=mocked_now)):
+            delete_xform_submissions(self.xform)
+
+        self.assertTrue(
+            all(instance.date_modified == mocked_now for instance in self.instances)
+        )
+
     def test_sets_deleted_by(self):
         """Deleted_by is set to the user who initiated the deletion"""
         delete_xform_submissions(self.xform, deleted_by=self.user)

onadata/libs/utils/logger_tools.py

@@ -1495,7 +1495,8 @@ def delete_xform_submissions(
         instances = xform.instances.filter(deleted_at__isnull=True)
 
     if soft_delete:
-        instances.update(deleted_at=timezone.now(), deleted_by=deleted_by)
+        now = timezone.now()
+        instances.update(deleted_at=now, date_modified=now, deleted_by=deleted_by)
     else:
         # Hard delete
         instances.delete()