#35996: Missing chunk_size throws exception when serializing many-to-many Model
field
-------------------------------------+-------------------------------------
Reporter: | Owner: ericapisani
ericapisani |
Type: Bug | Status: assigned
Component: Core | Version: 5.0
(Serialization) |
Severity: Release | Keywords:
blocker |
Triage Stage: | Has patch: 1
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
Related issue: https://code.djangoproject.com/ticket/35238
I'm currently upgrading a project from v4.x to v5.0.1 and, when attempting
to save a model with a prefetched many-to-many field, the "ValueError:
chunk_size must be provided when using QuerySet.iterator() after
prefetch_related()" exception is thrown within the core Django
[https://github.com/django/django/blob/9c436a09b3a641874881706495ae07293aa97c2f/django/core/serializers/python.py#L86
serializer]:
Here's the trace within my project that leads to the exception:
{{{
File ".../site-packages/django/db/models/base.py", line 822, in save
self.save_base(
File ".../site-packages/django/db/models/base.py", line 924, in
save_base
post_save.send(
File ".../site-packages/django/dispatch/dispatcher.py", line 189, in
send
response = receiver(signal=self, sender=sender, **named)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
# The revisions files below are referring to the django-reversion library
File ".../site-packages/reversion/revisions.py", line 340, in
_post_save_receiver
add_to_revision(instance, model_db=using)
File ".../site-packages/reversion/revisions.py", line 209, in
add_to_revision
_add_to_revision(obj, db, model_db, True)
File ".../site-packages/reversion/revisions.py", line 184, in
_add_to_revision
serialized_data=serializers.serialize(
^^^^^^^^^^^^^^^^^^^^^^
File ".../site-packages/django/core/serializers/__init__.py", line 134, in
serialize
s.serialize(queryset, **options)
File ".../site-packages/django/core/serializers/base.py", line 143, in
serialize
self.handle_m2m_field(obj, field)
File ".../site-packages/django/core/serializers/python.py", line 91, in
handle_m2m_field
queryset_iterator(obj, field),
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".../site-packages/django/core/serializers/python.py", line 86, in
queryset_iterator
.iterator()
^^^^^^^^^^
File ".../site-packages/django/db/models/query.py", line 532, in
iterator
raise ValueError(
ValueError: chunk_size must be provided when using QuerySet.iterator()
after prefetch_related().
}}}
I confirmed that applying the same fix as the issue linked above addresses
the issue.
**Proposed solution:**
I'm happy to put up a pull request with the patch, and can emulate what
the issue linked above did which is conditionally supply a `chunk_size`
similar to the solution implemented in the issue linked above'
--
Ticket URL: <https://code.djangoproject.com/ticket/35996>
Django <https://code.djangoproject.com/>
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