[Django] #21434: IN clause not supporting the to_field

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Nov 13, 2013, 7:38:31 PM11/13/13

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#21434: IN clause not supporting the to_field
-------------------------------+--------------------
Reporter: berndtj@… | Owner: nobody
Type: Bug | Status: new
Component: Uncategorized | Version: 1.5
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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I think this is similar to bug 17972.

If I have a model defined:

{{{
class VolumeTemplate(models.Model):
parent = models.ForeignKey(
'Volume', null=True, blank=True, to_field='uuid',
related_name='parent_templates')

class BracketVolume(models.Model):
uuid = UUIDField(version=4, auto=True, db_index=True, unique=True)
}}}

The following query returns an empty result set, even if the parent is non
None:

{{{
queryset = Volume.objects.all()
VolumeTemplate.objects.filter(parent__in=queryset)
}}}

However the following will return the corresponding VolumeTemplates:

{{{
VolumeTemplate.objects.filter(parent__pk__in=queryset)
}}}

This is because the subquery generated by the IN clause does not take the
to_field into consideration and instead returns a list of Volume.id values
instead of Volume.uuid values. The SQL is comparing the parent_id which
is a UUID field due to the to_field.

--
Ticket URL: <https://code.djangoproject.com/ticket/21434>
Django <https://code.djangoproject.com/>
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Django

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Nov 14, 2013, 9:23:01 AM11/14/13

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#21434: IN clause not supporting the to_field

Easy pickings: 0 | UI/UX: 0

-------------------------------------+-------------------------------------
Changes (by bmispelon):

* status: new => closed
* cc: bmispelon (added)
* needs_better_patch: => 0
* component: Uncategorized => Database layer (models, ORM)
* needs_tests: => 0
* needs_docs: => 0
* resolution: => fixed

Comment:

Hi,

I can indeed reproduce the issue on the 1.5 branch, using the two
following models:
{{{#!python
from django.db import models

class Foo(models.Model):
foo = models.CharField(max_length=1, db_index=True, unique=True)

class Bar(models.Model):
foo = models.ForeignKey(Foo, to_field='foo')
}}}
With these models, the following code shows the issue: `assert
Bar.objects.filter(foo__in=Foo.objects.all()).count()` (this requires
having created one model of each kind in the database).

Having this code, I was able to track down the commit that fixed this
issue in the master branch (also present in 1.6, as it turns out):
97774429aeb54df4c09895c07cd1b09e70201f7d.

Seeing as this issue is not a regression (and therefore its fix is
unlikely to get backported), I'm going to mark this ticket as `fixed`.
Feel free to reopen the ticket if you think otherwise of course.