The migration framework uniquely identifies models by case insensitive
labels composed of their app label and model names and so does the app
registry in most of its methods (e.g. AppConfig.get_model) but it
wasn't the case for get_swappable_settings_name() until this change.
This likely slipped under the radar for so long and only regressed in
b9df2b74b9 because prior to the changes
related to the usage of model states instead of rendered models in the
auto-detector the exact value settings value was never going through a
case folding hoop.
Thanks Andrew Chen Wang for the report and Keryn Knight for the
investigation.
This allows bringing back the behavior of Django < 1.7.
Also fixed the check for the app registry being ready in
AppConfig.get_model(s), which was inconsistent with the equivalent check in
Apps.get_model(s). That part is a backwards-incompatible change.
It was inconsistent with the equivalent check in Apps.get_model(s)
because I made incorrect assumptions when I wrote that code and
needlessly complicated readiness checks.
This is a backwards-incompatible change.
Moved the lookup in Field.swappable_setting to Apps, and added
an lru_cache to cache the results.
Refs #24743
Thanks Marten Kenbeek for the initial work on the patch. Thanks Aymeric
Augustin and Tim Graham for the review.
This adds a new method, Apps.lazy_model_operation(), and a helper function,
lazy_related_operation(), which together supersede add_lazy_relation() and
make lazy model operations the responsibility of the App registry. This
system no longer uses the class_prepared signal.
Set apps.ready to False when rendering multiple models. This prevents
that the cache on Model._meta is expired on all models after each time a
single model is rendered. Prevented that Apps.clear_cache() refills the
cache on Apps.get_models(), so that the wrong value cannot be cached
when cloning a StateApps.
Previously a RuntimeError was raised every time two models clashed
in the app registry. This prevented reloading a module in a REPL;
while it's not recommended to do so, we decided not to forbid this
use-case by turning the error into a warning.
Thanks @dfunckt and Sergey Pashinin for the initial patches.
Since the app registry is always populated before the first request is
processed, the situation described in #18251 for the old app cache
cannot happen any more.
Refs #18251, #21628.