#15200: ManyToManyField combined with "|" leads to trouble
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Reporter: vanschelven | Owner: nobody
Status: new | Milestone:
Component: Uncategorized | Version: 1.2
Keywords: | Triage Stage: Unreviewed
Has patch: 0 |
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!ManyToManyField combined with "|" leads to trouble.
Specifically, the outer join that appears to be constructed for manytomany
field lookups is not well cleaned up with where statements once an "or"
("|") is used.
{{{
$ cat theapp/models.py
from django.db import models
class AnObject(models.Model):
nr = models.IntegerField()
class HasRef(models.Model):
obj = models.ManyToManyField(AnObject)
field = models.IntegerField()
}}}
{{{
>>> from theapp.models import *
>>> one = AnObject.objects.create(nr=1)
>>> two = AnObject.objects.create(nr=2)
>>> reffer = HasRef.objects.create(field=1)
>>> reffer.obj.add(one)
>>> reffer.obj.add(two)
>>> HasRef.objects.all().filter(field=1)
[<HasRef: HasRef object>]
>>> HasRef.objects.all().filter(obj=one)
[<HasRef: HasRef object>]
>>> HasRef.objects.all().filter(models.Q(field=1) | models.Q(obj=one))
[<HasRef: HasRef object>, <HasRef: HasRef object>]
>>> [o.pk for o in HasRef.objects.all().filter(models.Q(field=1) |
models.Q(obj=one))]
[1L, 1L]
}}}
I don't have the time right now to come up with tests proper, or a patch.
The problem is real though...
My workaround:
{{{
>>> HasRef.objects.all().filter(models.Q(field=1) |
models.Q(obj=one)).annotate(models.Count("id"))
}}}
The generated query (without workaround)
{{{
>>> print HasRef.objects.all().filter(models.Q(field=1) |
models.Q(obj=AnObject.objects.get(nr=1))).query
SELECT `theapp_hasref`.`id`, `theapp_hasref`.`field` FROM `theapp_hasref`
LEFT OUTER JOIN `theapp_hasref_obj` ON (`theapp_hasref`.`id` =
`theapp_hasref_obj`.`hasref_id`) WHERE (`theapp_hasref`.`field` = 1 OR
`theapp_hasref_obj`.`anobject_id` = 1 )
}}}
{{{
--
Ticket URL: <http://code.djangoproject.com/ticket/15200>
Django <http://code.djangoproject.com/>
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