#10304: topics/db/queries.txt about delete() lies!
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Reporter: telenieko | Owner: nobody
Status: closed | Milestone:
Component: Database layer (models, ORM) | Version: 1.0
Resolution: invalid | Keywords: delete
Stage: Unreviewed | Has_patch: 0
Needs_docs: 0 | Needs_tests: 0
Needs_better_patch: 0 |
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Changes (by kmtracey):
* status: new => closed
* needs_better_patch: => 0
* resolution: => invalid
* needs_tests: => 0
* needs_docs: => 0
Comment:
I haven't looked at the !QuerySet code but a little shell experimentation
shows that it is not impossible to avoid calling delete() of every single
object. Given this model:
{{{
#!python
class DT(models.Model):
name = models.CharField(max_length=5)
def delete(self):
print 'Delete for %s called' % self.name
super(DT, self).delete()
def __unicode__(self):
return self.name
}}}
and this shell session:
{{{
Python 2.5.1 (r251:54863, Jul 31 2008, 23:17:40)
[GCC 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> import django
>>> django.get_version()
u'1.1 pre-alpha SVN-9841'
>>> from ttt.models import DT
>>> DT.objects.create(name='x')
<DT: x>
>>> DT.objects.create(name='y')
<DT: y>
>>> DT.objects.create(name='z')
<DT: z>
>>> DT.objects.all()
[<DT: x>, <DT: y>, <DT: z>]
>>> x = DT.objects.all()[0]
>>> x.delete()
Delete for x called
>>> DT.objects.all()
[<DT: y>, <DT: z>]
>>> DT.objects.all().delete()
>>> DT.objects.all()
[]
>>>
}}}
The individual delete() method was not called for
`DT.objects.all().delete()`.
(Even if it was the case that the code as written now always guaranteed
the individual delete() methods were called, the doc would not be wrong.
It is warning that the individual delete() may not be called when objects
are deleted in bulk, it doesn't say it absolutely will not be called.)
--
Ticket URL: <http://code.djangoproject.com/ticket/10304#comment:1>
Django <http://code.djangoproject.com/>
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