While refs #34612 surfaced issues with reverse one-to-one fields
deferrals, it missed that switching to storing remote fields would break
self-referential relationships.
This change switches to storing related objects in the select mask
instead of remote fields to prevent collisions when dealing with
self-referential relationships that might have a different directional
mask.
Despite fixing #21204 introduced a crash under some self-referential
deferral conditions, it was simply not working even before that as it
aggregated the sets of deferred fields by model.
Thanks Joshua van Besouw for the report and Mariusz Felisiak for the
review.
Regression in b3db6c8dcb.
Thanks Ian Cubitt for the report.
This also corrected test_inheritance_deferred2() test which was
previously properly defined and marked as an expected failure but was
then wrongly adjusted to mask the lack of support for per-alias
deferral that was fixed by #21204.
While deferring many-to-many and GFK has no effect, the previous
implementation of QuerySet.defer() ignore them instead of crashing.
Regression in b3db6c8dcb.
Thanks Paco Martínez for the report.
Refactored compiler SELECT, GROUP BY and ORDER BY generation.
While there, also refactored select_related() implementation
(get_cached_row() and get_klass_info() are now gone!).
Made get_db_converters() method work on expressions instead of
internal_type. This allows the backend converters to target
specific expressions if need be.
Added query.context, this can be used to set per-query state.
Also changed the signature of database converters. They now accept
context as an argument.
Surprisingly, this commit doesn't change any behavior at all. When a
model is defined with the same name as another model in the same app,
the definition of the first class is bound to the name of the class
regardless of the definition of the second class.
Since the original ones in django.db.models.loading were kept only for
backwards compatibility, there's no need to recreate them. However, many
internals of Django still relied on them.
They were also imported in django.db.models. They never appear in the
documentation, except a quick mention of get_models and get_app in the
1.2 release notes to document an edge case in GIS. I don't think that
makes them a public API.
This commit doesn't change the overall amount of global state but
clarifies that it's tied to the app_cache object instead of hiding it
behind half a dozen functions.
Added settings.SESSION_SERIALIZER which is the import path of a serializer
to use for sessions.
Thanks apollo13, carljm, shaib, akaariai, charettes, and dstufft for reviews.
Correctly calculate the ``aggregate_start`` offset from loaded fields,
if any are deferred, instead of ``self.query.select`` which includes all
fields on the model.
Also made some PEP 8 fixes.
