#11606: return error data when using only() and select_related() at the same
times
that models foreign key is set to default null.
---------------------------------------------------+------------------------
Reporter: seandong | Owner: nobody
Status: new | Milestone:
Component: Database layer (models, ORM) | Version: SVN
Resolution: | Keywords:
only,select_related,defer
Stage: Accepted | Has_patch: 0
Needs_docs: 0 | Needs_tests: 0
Needs_better_patch: 0 |
---------------------------------------------------+------------------------
Changes (by brutasse):
* cc: [email protected] (added)
Comment:
I have tried to look at this without success. It seems that the generated
SQL is perfectly fine but some columns get mixed when building the python
representation.
I have some models that looks like this:
{{{
#!python
class Category(models.Model):
color = models.CharField(max_length=50)
class Feed(models.Model):
name = models.CharField(max_length=255)
category = models.ForeignKey(Category, related_name='feeds')
class Entry(models.Model):
feed = models.ForeignKey(Feed, related_name='entries')
title = models.CharField(max_length=255)
date = models.DateTimeField()
read = models.BooleanField(default=False, db_index=True)
user = models.ForeignKey(User, related_name='entries')
}}}
If I do:
{{{
#!python
entries = Entry.objects.select_related().only('id', 'feed', 'title',
'date',
'read', 'feed__name',
'feed__category__color')
}}}
then:
{{{
#!python
for e in entries:
print e.feed.category.color # prints datetime.datetime instances (all
the same) - related user's creation date
print e.feed.category.id # prints the related user's password hash
sha1$cf481$01b13cdfab3.....
}}}
So, the problem may not be specific to foreign keys, and the engine
fetches information from wrong related tables.
This happens at least on PostgreSQL, I can't confirm on other backends.
--
Ticket URL: <http://code.djangoproject.com/ticket/11606#comment:2>
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