post_save signal is not called when LogEntry has Deletion action

[smiling-watermelon]

I've added a post_save signal for my application to show LogEntry entities in my logs, but have ran into the following problem:
If I remove some object from admin, LogEntry with Deletion action is created and stored in the database, but my post_save signal is not called.

I've ensured that other actions are working fine:

• Addition
• Change

So, for some reason only "Deletion" action doesn't cause the post_save signal to be called.

To help reproduce the issue I've created a small ​repository on GitHub (basically following Django's documentation on creating a project), and added my signal there.

If you need any more info from me, just let me know, hopefully the README is pretty easy to follow and understand.

The exact Django version I've been using is 5.1.6, in both - the demo (though there it's not pinned!) and my real project.

[Sarah Boyce]

Thank you for the ticket!

I think this is a consequence of 40b3975e7d3e1464a733c69171ad7d38f8814280 (#34462), as we now use bulk_create which doesn't send a post_save signal (​see bulk_create docs).

The single_object kwarg, which decides to use .save() (and send signals), is used for log_addition etc but never for log_deletions (even if this is only one object). I believe this is an inconsistency of behavior we might want to clean up.

I also think that we perhaps should/could document that these signals are no longer sent as part of the backwards incompatible changes of Django 5.1 (with maybe an alternative suggestion).

Note that it wasn't clear to me why we can't remove single_object kwarg entirely (I'm likely missing something):

django/contrib/admin/models.py

@@ -24 +24 @@
 class LogEntryManager(models.Manager):
     use_in_migrations = True
 
-    def log_actions(
-        self, user_id, queryset, action_flag, change_message="", *, single_object=False
-    ):
+    def log_actions(self, user_id, queryset, action_flag, change_message=""):
         if isinstance(change_message, list):
             change_message = json.dumps(change_message)
 
@@ -44 +42 @@
             for obj in queryset
         ]
 
-        if single_object and log_entry_list:
+        if len(log_entry_list) == 1:
             instance = log_entry_list[0]
             instance.save()
             return instance

[Antoliny]

Replying to Sarah Boyce:

Thank you for the ticket!

I think this is a consequence of 40b3975e7d3e1464a733c69171ad7d38f8814280 (#34462), as we now use bulk_create which doesn't send a post_save signal (​see bulk_create docs).

The single_object kwarg, which decides to use .save() (and send signals), is used for log_addition etc but never for log_deletions (even if this is only one object). I believe this is an inconsistency of behavior we might want to clean up.

I also think that we perhaps should/could document that these signals are no longer sent as part of the backwards incompatible changes of Django 5.1 (with maybe an alternative suggestion).

Note that it wasn't clear to me why we can't remove single_object kwarg entirely (I'm likely missing something):

So, does that mean that from now on, bulk_create will always be used regardless of the number of objects being added or changed, and signals will never be triggered?

[Sarah Boyce]

So, does that mean that from now on, bulk_create will always be used regardless of the number of objects being added or changed, and signals will never be triggered?

Right now, save(), which sends the signals, is used when single_object=True.
This is used by log_addition and log_change. This is not used by log_deletions (which makes sense as it can have multiple objects).
But log_deletions is called with a single object in django.contrib.admin.options.ModelAdmin._delete_view. To me, it is inconsistent that we use save and send signals in the other cases, but not here.

[Sarah Boyce <42296566+sarahboyce@…>]

In c09bceef:

Fixed #36217 -- Restored pre_save/post_save signal emission via LogEntry.save() for single-object deletion in the admin.

Regression in 40b3975e7d3e1464a733c69171ad7d38f8814280.

Thanks smiling-watermelon for the report.

Co-authored-by: Sarah Boyce <42296566+sarahboyce@…>

[Sarah Boyce <42296566+sarahboyce@…>]

In 5997fdc9:

[5.2.x] Fixed #36217 -- Restored pre_save/post_save signal emission via LogEntry.save() for single-object deletion in the admin.

Regression in 40b3975e7d3e1464a733c69171ad7d38f8814280.

Thanks smiling-watermelon for the report.

Co-authored-by: Sarah Boyce <42296566+sarahboyce@…>

Backport of c09bceef68e5abb79accedd12dade16aa6577a09 from main.

[Sarah Boyce <42296566+sarahboyce@…>]

In 03ace75:

[5.1.x] Fixed #36217 -- Restored pre_save/post_save signal emission via LogEntry.save() for single-object deletion in the admin.

Regression in 40b3975e7d3e1464a733c69171ad7d38f8814280.

Thanks smiling-watermelon for the report.

Co-authored-by: Sarah Boyce <42296566+sarahboyce@…>

Backport of c09bceef68e5abb79accedd12dade16aa6577a09 from main.