update_or_create(defaults=None) sends update_fields=set() rather than None

[jacobtylerwalls]

I’ll probably just do the strictly incorrect thing only temporarily, emit warnings, and allow time for update_or_create() callsites to determine if they really need the injected fields from the save() call or not. Should eventually get correctness that way

I agree with the following from the last time I asked for advice on this topic:

@charettes

With JSONField maturing in core without proper update_fields={'json_field__key'} support and a long standing desire to entirely replace auto_now and friends with fields that use default but have a way to opt-in into update_fields injection I think we’ll want to revisit how this feature is implemented in the future.

I’m not convinced that a core function is warranted here. I think it might be better to invest efforts in coming up with a generic solution to the problem of derived / generated fields and their interactions with update_fields.

Maybe the next stop should be a new-features repo ticket to sound out what that generic solution might look like?

---

Finally, should we update the pseudocode in the docs for update_or_create() to stop showing save() given that it’s described here as an implementation detail?