#12851: Queryset "defer" won't work properly with select_related
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Reporter: ruosteinen | Owner: nobody
Status: new | Milestone:
Component: Database layer (models, ORM) | Version: 1.2-beta
Keywords: select_related, defer, nesting, query | Stage: Unreviewed
Has_patch: 0 |
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Select_related and defer don't seem to work properly together. Consider
following models in APP '''buggy'''.
{{{
from django.db import models
class ProblemModel(models.Model):
name = models.CharField(max_length=100)
target = models.ForeignKey('Target', null=True)
class Target(models.Model):
location = models.CharField(max_length=100)
}}}
Even though Queryset API document the use of underscore in deferring, the
following ends up in assertion error.
{{{
from buggy.models import Target, ProblemModel
Target.objects.all().delete(); ProblemModel.objects.all().delete()
tgt = Target.objects.create(location='Earth')
pm = ProblemModel.objects.create(name='bug', target=tgt)
pm =
ProblemModel.objects.select_related('target').defer('target__location').get(name='bug')
assert pm.target.location == 'bug'
}}}
At least according to Queryset API docs, defer() is supposed to allow
access to deferred fields even if they're not loaded initially.
In addition pm.target is not of type Target_Deferred_location_deferred as
it should be(?). There seem to be some other weirdness as well with
select_related and defer but they'll probably be fixed once nesting works
properly.
This in Django 1.2 beta 1 SVN-12416
I'll start working on a patch right away.
-Tommi Penttinen-
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Ticket URL: <http://code.djangoproject.com/ticket/12851>
Django <http://code.djangoproject.com/>
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