#14177: Out of date cache on django.db.models.options.Options instance after
adding
ForeignKey at runtime
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Reporter: anonymous | Owner: nobody
Status: new | Milestone:
Component: Database layer (models, ORM) | Version: 1.1
Keywords: | Stage: Unreviewed
Has_patch: 0 |
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{{{
--- <bash session> ---
localhost:~$ django-admin.py startproject dbg
localhost:~$ cd dbg/
localhost:~/dbg$ python manage.py startapp myapp
localhost:~/dbg$ echo "from django.db import models
class SomeObject(models.Model):
title = models.TextField()
class SomeItem(models.Model):
someint = models.IntegerField()" > myapp/models.py
localhost:~/dbg$ echo "from myapp.models import *
try:
SomeObject.objects.annotate(models.Avg('items__someint'))
except Exception as e:
print e, '(Obviously, because relation to items is not defined)'
SomeItem.add_to_class('object', models.ForeignKey(SomeObject,
related_name='items'))
try:
SomeObject.objects.annotate(models.Avg('items__someint'))
except Exception as e:
print e, \"(Doesn't work because cache in SomeObject._meta is not
updated after SomeItem.add_to_class call.)\"
print 'It seems that forcing cache on SomeObject._meta to reload fixes the
problem.'
del SomeObject._meta._name_map
del SomeObject._meta._related_objects_cache
print SomeObject.objects.annotate(models.Avg('items__someint')),
'(Working!)'
from django.db import connection
print connection.queries[-1]['sql']" > test.py
localhost:~/dbg$ export DJANGO_SETTINGS_MODULE="settings"
localhost:~/dbg$ sed -i s/"DATABASE_ENGINE.*"/"DATABASE_ENGINE =
'sqlite3'"/g settings.py
localhost:~/dbg$ sed -i s/"DATABASE_NAME.*"/"DATABASE_NAME = 'db'"/g
settings.py
localhost:~/dbg$ python ./test.py
Cannot resolve keyword 'items' into field. Choices are: id, title
(Obviously, because relation to items is not defined)
Cannot resolve keyword 'items' into field. Choices are: id, title
(Doesn't work because cache in SomeObject._meta is not updated after
SomeItem.add_to_class call.)
It seems that forcing cache on SomeObject._meta to reload fixes the
problem.
[] (Working!)
SELECT "myapp_someobject"."id", "myapp_someobject"."title",
AVG("myapp_someitem"."someint") AS "items__someint__avg" FROM
"myapp_someobject" LEFT OUTER JOIN "myapp_someitem" ON
("myapp_someobject"."id" = "myapp_someitem"."object_id") GROUP BY
"myapp_someobject"."id", "myapp_someobject"."title" LIMIT 21
--- </bash session> ---
}}}
--
Ticket URL: <http://code.djangoproject.com/ticket/14177>
Django <http://code.djangoproject.com/>
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