#6095: Add the ability to manually create M2M intermediary models
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Reporter: jacob | Owner: floguy
Status: reopened | Milestone: 1.0 beta
Component: Database wrapper | Version: SVN
Resolution: | Keywords:
Stage: Accepted | Has_patch: 1
Needs_docs: 1 | Needs_tests: 0
Needs_better_patch: 1 |
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Comment (by Rob Hudson <[EMAIL PROTECTED]>):
It's getting late and I don't have time to test this fully, but I think I
found a bug. The only major difference I can see in my case and the
example is that one of my models is in another app separate from the 2
models. For example:
{{{
# In myproject/clip/models.py
class Clip(models.Model):
title = models.CharField(max_length=200)
# In myproject/presentation/models.py
from myproject.clip.models import Clip
class Presentation(models.Model):
title = models.CharField(max_length=200)
clips = models.ManyToManyField(Clip, through='Sequence')
class Sequence(models.Model):
presentation = models.ForeignKey(Presentation)
clip = models.ForeignKey(Clip)
sequence = models.IntegerField(blank=True, null=True)
}}}
The error I'm getting is this:
{{{
Traceback:
File "/Users/rob/sandbox/django/django_trunk/django/core/handlers/base.py"
in get_response
86. response = callback(request, *callback_args,
**callback_kwargs)
File
"/Users/rob/sandbox/django/django_trunk/django/contrib/admin/views/decorators.py"
in _checklogin
62. return view_func(request, *args, **kwargs)
File
"/Users/rob/sandbox/django/django_trunk/django/contrib/admin/views/main.py"
in change_stage
372. new_data = manipulator.flatten_data()
File
"/Users/rob/sandbox/django/django_trunk/django/db/models/fields/related.py"
in flatten_data
856. instance_ids = [instance._get_pk_val() for instance in
getattr(obj, self.name).all()]
File
"/Users/rob/sandbox/django/django_trunk/django/db/models/fields/related.py"
in __get__
543. target_col_name=qn(self.field.m2m_reverse_name())
File
"/Users/rob/sandbox/django/django_trunk/django/db/models/fields/related.py"
in _get_m2m_reverse_name
829. return related.field.get_attname_column()[1]
Exception Type: AttributeError at /admin/presentation/presentation/1/
Exception Value: 'NoneType' object has no attribute 'field'
}}}
Inside the _get_m2m_reverse_name method is this if block.
{{{
if self.rel.through is not None:
meta = related.parent_model._meta
if self.parent == self.rel.to:
related = meta.get_related_object(self.rel.through,
self_ref = True)
else:
related = meta.get_related_object(self.rel.through)
return related.field.get_attname_column()[1]
}}}
My self.rel.through is 'Sequence' which has a FK to Presentation (the same
app) and an FK to Clip (different app) plus an integer that's the sequence
used to order the clips of a presentation. The meta of the 2nd line if
printed is 'clip.clip'. But if I get a Clip object and try to call
c._meta.get_related_object('Sequence') on it, I get nothing back. If,
however, I call the same on a Presentation object, I do get RelatedObject
back.
I can supply more details if needed. Is this supposed to work across
apps? Anything I'm doing wrong here?
--
Ticket URL: <http://code.djangoproject.com/ticket/6095#comment:65>
Django Code <http://code.djangoproject.com/>
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