#24523: django.apps.registry.populate() does not handle failures in
app_config.ready()
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Reporter: kalium99 | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Core (Other) | Version: master
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by kalium99):
Replying to [comment:10 shaib]:
> I suspect this report to be invalid.
>
> Just above the quoted note in `AppConfig.ready()`'s documentation,
there's a warning: Avoid interacting with the database. The whole point of
this report is "ready() failed when interacting with the database".
>
Hi,
I'm not sure where that above quoted text is from, and the whole point of
this report is certainly not that ready() failed when interacting with the
database.
The whole point of this bug report is that the code does one or more of
the following:
1) Gives really unhelpful errors that do not confer the cause of the
problem.
2) The specific block of code in DJango does not actually work in the way
it was intended.
> The issue is "concealed" because the app whose `ready()` happened to
interact with the database is `django.contrib.admin`; the interaction
happened because, as appears in the log above,
> {{{
> [Sun Mar 22 23:47:26 2015] [error] [client 127.0.0.1] File
"/home/test/apps/partners/forms.py", line 44, in PartnerSelection
> [Sun Mar 22 23:47:26 2015] [error] [client 127.0.0.1] (p.id,
p.company_name) for p in Partner.objects.all()])
> }}}
> a query is executed in the import of a forms.py file.
>
> The code is, of course, cut, but this looks like a "choices" argument,
and if so, it is not only a problem because of database-interaction-
in-`ready()`, but because it is a classic application bug -- if you add a
Partner, it won't show in the form; the form only lets you select the
partners that were recorded when the app started. To solve both issues,
use a `ModelChoiceField` instead.
>
Both of these points are well understood and accepted. In fact in an
earlier message I said "Technically you could say this is NOTABUG, because
the method clearly says it is not re-entrant. " , as well as saying "This
situation is not ideal for a couple of reasons (not in the least that the
field is not updated until a process is recycled)."
This ticket is about the interplay between the 'app_config' and 'ready'
variables, and how perhaps they don't work quite as intended, and how
changing the error message, or the code itself, could give a better user
experience in such circumstances.
--
Ticket URL: <https://code.djangoproject.com/ticket/24523#comment:11>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
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