#23624: Regression in ManyToManyField with through, runtime-generated models
-------------------------------------+-------------------------------------
Reporter: ludoo | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.7
(models, ORM) | Resolution:
Severity: Normal | Triage Stage:
Keywords: | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by ludoo:
Old description:
> I admit my situation is a corner case: an app interfacing with a legacy
> db, where I need to extend an abstract model to contextualize it to
> identical tables, named differently (eg obj_1 table, obj_2 table, etc.),
> and to make things worse the number of tables is only known at runtime.
>
> I am then dynamically generating a module for each set of models, and
> while things work great in Django 1.6, in 1.7 ManyToManyField using a
> through model breaks.
>
> I am attaching a sample models.py file that illustrates the issue. I have
> not yet found the time to delve into what's happening, I hope someone
> with a better understanding of all the related stuff steps in as it's
> something I have never looked into.
New description:
I admit my situation is a corner case: an app interfacing with a legacy
db, where I need to extend an abstract model to contextualize it to
identical tables, named differently (eg obj_1 table, obj_2 table, etc.),
and to make things worse the number of tables is only known at runtime.
I am then dynamically generating a module for each set of models, and
while things work great in Django 1.6, in 1.7 ManyToManyField using a
through model breaks.
I am attaching a sample models.py file that illustrates the issue. I have
not yet found the time to delve into what's happening, I hope someone with
a better understanding of all the related stuff steps in as it's something
I have never looked into.
What happens is that the manager seems to ignore the through model, here
is the traceback (actual call and models in the attached file):
{{{
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/manager.py", line 191, in all
return self.get_queryset()
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/fields/related.py", line 887, in get_queryset
return qs._next_is_sticky().filter(**self.core_filters)
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/query.py", line 691, in filter
return self._filter_or_exclude(False, *args, **kwargs)
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/query.py", line 709, in _filter_or_exclude
clone.query.add_q(Q(*args, **kwargs))
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/sql/query.py", line 1287, in add_q
clause, require_inner = self._add_q(where_part, self.used_aliases)
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/sql/query.py", line 1314, in _add_q
current_negated=current_negated, connector=connector)
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/sql/query.py", line 1138, in build_filter
lookups, parts, reffed_aggregate = self.solve_lookup_type(arg)
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/sql/query.py", line 1076, in solve_lookup_type
_, field, _, lookup_parts = self.names_to_path(lookup_splitted,
self.get_meta())
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/sql/query.py", line 1383, in names_to_path
self.raise_field_error(opts, name)
File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-
packages/django/db/models/sql/query.py", line 1389, in raise_field_error
"Choices are: %s" % (name, ", ".join(available)))
FieldError: Cannot resolve keyword u'a' into field. Choices are: a_s, id,
name
}}}
--
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Ticket URL: <https://code.djangoproject.com/ticket/23624#comment:2>
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