aiterator() missing check for chunk_size=None after prefetch_related()

[Jacob Walls]

aiterator() is missing the ​check found in iterator() for chunk_size=None after prefetch_related():

iterator() version:

        if chunk_size is None:
            if self._prefetch_related_lookups:
                raise ValueError(
                    "chunk_size must be provided when using QuerySet.iterator() after "
                    "prefetch_related()."
                )

I think this should have been implemented in #34331.

The rationale for the check was to alert users that the number of queries could spike with small batch sizes, which you might be tempted to minimize if prioritizing memory optimizations.

[zky]

​https://github.com/django/django/pull/21425

[Jacob Walls]

Needs a release note, and now that I think of it, probably a deprecation path as well given that we accidentally supported this.

[zky]

Replying to Jacob Walls:

Needs a release note, and now that I think of it, probably a deprecation path as well given that we accidentally supported this.

I have changed the behavior from raising an exception to issuing a deprecation warning.And I have also added/updated the documentation.

[Jacob Walls <jacobtylerwalls@…>]

In ca5746b:

Fixed #37143 -- Added missing chunk_size=None check to QuerySet.aiterator().

Co-authored-by: Jacob Walls <jacobtylerwalls@…>