id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
24231	Regression in availability of `_meta.get_field()` before app registry is fully populated	Carl Meyer	nobody	"In Django versions prior to 1.8, it was possible to call `_meta.get_field(...)` on a model class before the app registry was fully populated -- for instance, in a `class_prepared` signal handler that adjusts a model's fields or adds new field(s). (Real-world example: https://github.com/carljm/django-model-utils/blob/master/model_utils/models.py#L54-L94)

In 1.8, with the meta refactor, this now raises an `AppRegistryError`.

This change makes sense, because `get_field` also gets reverse related fields, and those can't be populated until all models are done loading. But it's still a regression in a reasonable use case (even though the meta API was technically private before, it was de facto public).

I think the issue of ""when are these methods safe to call?"" should be discussed in the _meta refactor porting guide, because it has changed from 1.7, even for methods like `get_field()` that otherwise remain similar.

I also think there should be some public supported, documented API that is safe to use before the app registry is populated, that accesses only fields declared on the local model. Perhaps an API equivalent to what you can currently do with `_meta._get_fields(reverse=False)`. (I note that this last is already used several places in Django internally where local fields need to be accessed before the app registry is ready.)"	Bug	closed	Documentation	1.8alpha1	Normal	wontfix	1.8-beta	pirosb3	Accepted	1	0	0	1	0	0