[BUG?] post_publish Signal replacement arguments

[Will-Hoey]

As of CMS v4, the publish signals have been moved into versioning. In one of our projects we use django-elasticsearch-dsl in order to search on Title/PageContent objects. We used the signals to update the index on Page publish/unpublish.

def setup(self):
    super().setup()
    post_unpublish.connect(self.handle_save)
    post_publish.connect(self.handle_save)

Which roughly translates to

def setup(self):
    super().setup()
    post_version_operation.connect(self.handle_save)

However, there is a small difference in the way that the signals are sent
https://github.com/django-cms/django-cms/blob/release/3.11.x/cms/models/pagemodel.py#L1007 vs

djangocms-versioning/djangocms_versioning/operations.py

Line 40 in f31b5e0

obj=version,

The old way seems to adhere more to what libraries like Elasticsearch are expecting by sending instance as the arg rather than the new obj.

Happy to work around this if there are other reasons why this was changed, just curious if this was an intended decision?

Note:
Workaround this by overriding the handle_save method in the SignalProcessor from django-elasticsearch-dsl to account for either the instance or obj arguments.

def handle_save(self, sender, instance=None, **kwargs):
    """Handle save.

    Given an individual model instance, update the object in the index.
    Update the related objects either.
    """
    instance = instance or kwargs.get("obj")
    super().handle_save(sender, instance, **kwargs)
``

[Will-Hoey]

@fsbraun any thoughts on this?

(Sorry not sure if you're the right person to tag!)

[marksweb]

@Will-Hoey Fabian certainly is the right person to tag. Our expert in the majority of things these days.

[fsbraun]

@Will-Hoey Sorry, I don't know why the signature changed. (Most of what I know is there's been a change to the signals here: #348).

We need to assume that the current signal signatures are used. If there is a good reason to change it, we would need a deprecation period, during which both signatures work. That would require to send both obj and instance parameters. I am not sure if that will cause any side effects.

[Will-Hoey]

@fsbraun Not a problem. We can work around this for now as we don't use it all that often. Thanks for the reply.