#26092: Regression when using order_by() on a ManyToManyField using the
'through'
feature
----------------------------------------------+--------------------
Reporter: wjakob | Owner: nobody
Type: Bug | Status: new
Component: Database layer (models, ORM) | Version: 1.9
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
----------------------------------------------+--------------------
Hi,
I'm seeing a serious regression (AttributeError exception thrown) when
using the order_by() feature on a ManyToManyField in combination with the
'through' feature.
This worked perfectly fine in Django 1.8.x, I'm seeing it for the first
time now. IMHO it is a release blocker, but then the release is already
out (so I set the severity as 'Normal').
See below for a minimal example:
{{{#!python
from django.db import models
class Person(models.Model):
name = models.CharField(max_length=200)
class Publication(models.Model):
title = models.CharField(max_length=200)
authors = models.ManyToManyField(Person, through='Author')
def get_authors(self):
return self.authors.order_by('author_to_publication')
class Author(models.Model):
person = models.ForeignKey(Person, verbose_name='Author',
related_name='author_to_publication')
publication = models.ForeignKey(Publication,
verbose_name='Publication')
order_id = models.PositiveSmallIntegerField(default=0)
class Meta:
ordering = ['order_id']
}}}
And here is an example shell session which causes the problem
{{{#!python
% ./manage.py shell
[INS]
Python 3.4.3 (v3.4.3:9b73f1c3e601, Feb 23 2015, 02:52:03)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>>
>>> person = myapp.models.Person()
>>> person.save()
>>>
>>> publication = myapp.models.Publication(title='test publication')
>>> publication.save()
>>> author = myapp.models.Author(person=person, publication=publication,
order_id=1)
>>> author.save()
>>>
>>> publication.authors.order_by('author_to_publication')
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/Users/wenzel/mysite/lib/python3.4/site-
packages/django/db/models/query.py", line 234, in __repr__
data = list(self[:REPR_OUTPUT_SIZE + 1])
File "/Users/wenzel/mysite/lib/python3.4/site-
packages/django/db/models/query.py", line 258, in __iter__
self._fetch_all()
File "/Users/wenzel/mysite/lib/python3.4/site-
packages/django/db/models/query.py", line 1074, in _fetch_all
self._result_cache = list(self.iterator())
File "/Users/wenzel/mysite/lib/python3.4/site-
packages/django/db/models/query.py", line 52, in __iter__
results = compiler.execute_sql()
File "/Users/wenzel/mysite/lib/python3.4/site-
packages/django/db/models/sql/compiler.py", line 837, in execute_sql
sql, params = self.as_sql()
File "/Users/wenzel/mysite/lib/python3.4/site-
packages/django/db/models/sql/compiler.py", line 382, in as_sql
extra_select, order_by, group_by = self.pre_sql_setup()
File "/Users/wenzel/mysite/lib/python3.4/site-
packages/django/db/models/sql/compiler.py", line 49, in pre_sql_setup
order_by = self.get_order_by()
File "/Users/wenzel/mysite/lib/python3.4/site-
packages/django/db/models/sql/compiler.py", line 295, in get_order_by
field, self.query.get_meta(), default_order=asc))
File "/Users/wenzel/mysite/lib/python3.4/site-
packages/django/db/models/sql/compiler.py", line 571, in
find_ordering_name
if field.is_relation and path and opts.ordering and name !=
field.attname:
AttributeError: 'ManyToOneRel' object has no attribute 'attname'
>>>
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/26092>
Django <https://code.djangoproject.com/>
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