id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
14535	Model.objects.all() causing ImportError in Django 1.2.3 in stand-alone script	benedikt	nobody	"After upgrading Ubuntu from Lucid to Maverick I have stumbled upon what seems to be a bug. Consider this stand-alone script that talks to a Django application, where Source is a Model object. Feedparser is a python module that parses RSS feeds (www.feedparser.org). 

{{{
>>> from feedparser import feedparser
>>> from django.core.management import setup_environ
>>> import os, sys
>>> sys.path.append('/home/benedikt/repos/frettaveita/')
>>> os.environ['DJANGO_SETTINGS_MODULE'] = 'settings' 
>>> import settings        
>>> from newsaggregator.models import Source
>>> mbl = Source.objects.get(name = 'mbl-innlent')
}}}

The normal behavior would be that mbl now is the Source object with the name 'mbl-innlent'. This however doesn't happen, but instead a ImportError is thrown and a rather large Traceback is printed. 

{{{
>>> mbl = Source.objects.get(name = 'mbl-innlent')
Traceback (most recent call last):
  File ""<stdin>"", line 1, in <module>
  File ""/usr/lib/pymodules/python2.6/django/db/models/manager.py"", line 132, in get
    return self.get_query_set().get(*args, **kwargs)
  File ""/usr/lib/pymodules/python2.6/django/db/models/query.py"", line 333, in get
    clone = self.filter(*args, **kwargs)
  File ""/usr/lib/pymodules/python2.6/django/db/models/query.py"", line 550, in filter
    return self._filter_or_exclude(False, *args, **kwargs)
  File ""/usr/lib/pymodules/python2.6/django/db/models/query.py"", line 568, in _filter_or_exclude
    clone.query.add_q(Q(*args, **kwargs))
  File ""/usr/lib/pymodules/python2.6/django/db/models/sql/query.py"", line 1128, in add_q
    can_reuse=used_aliases)
  File ""/usr/lib/pymodules/python2.6/django/db/models/sql/query.py"", line 1026, in add_filter
    negate=negate, process_extras=process_extras)
  File ""/usr/lib/pymodules/python2.6/django/db/models/sql/query.py"", line 1179, in setup_joins
    field, model, direct, m2m = opts.get_field_by_name(name)
  File ""/usr/lib/pymodules/python2.6/django/db/models/options.py"", line 291, in get_field_by_name
    cache = self.init_name_map()
  File ""/usr/lib/pymodules/python2.6/django/db/models/options.py"", line 321, in init_name_map
    for f, model in self.get_all_related_m2m_objects_with_model():
  File ""/usr/lib/pymodules/python2.6/django/db/models/options.py"", line 396, in get_all_related_m2m_objects_with_model
    cache = self._fill_related_many_to_many_cache()
  File ""/usr/lib/pymodules/python2.6/django/db/models/options.py"", line 410, in _fill_related_many_to_many_cache
    for klass in get_models():
  File ""/usr/lib/pymodules/python2.6/django/db/models/loading.py"", line 167, in get_models
    self._populate()
  File ""/usr/lib/pymodules/python2.6/django/db/models/loading.py"", line 61, in _populate
    self.load_app(app_name, True)
  File ""/usr/lib/pymodules/python2.6/django/db/models/loading.py"", line 76, in load_app
    app_module = import_module(app_name)
  File ""/usr/lib/pymodules/python2.6/django/utils/importlib.py"", line 35, in import_module
    __import__(name)
ImportError: No module named frettaveita.newsaggregator
>>> 
}}} 

If, however, we try the same piece of code a second time, right after the failed attempt it works, such as

{{{
>>> mbl = Source.objects.get(name = 'mbl-innlent')
>>> mbl
<Source: mbl-innlent>
>>> 
}}}

This was also the behavior in the Django 1.1.1, supplied with Ubuntu Lucid. The workaround is simple but ugly

{{{
try:
    mbl = Source.objects.get(name='mbl-innlent')
except ImportError:
    mbl = Source.objects.get(name='mbl-innlent')
}}}

since it will work in the second try if the first one fails. I have not been able to pinpoint the bug yet or patch it. However, I am not sure if this is a regression or if this is indeed the expected behavior. "		closed	Database layer (models, ORM)	1.2		invalid	ImportError, objects.all, maverick		Unreviewed	0	0	0	0	0	0