quoted class names in foreign key definition causes 'str' object has no attribute '_default_manager'

[danbrwn]

Myself and another discovered the following error with the code shown. In both cases we had quoted strings for reference class. In both cases importing the specific class and then referencing without the quotes solved the problem. I tried through IRC channel to get a resolution. Downloaded code, wiped out site-packages/django dir before running setup, took other suggestions. Nothing worked except removing the quotes as suggested on the django-users group. I am running Debian Etch final. Python 2.5 and Django 1.0.2, Apache2 with mod_python
AttributeError: 'str' object has no attribute '_default_manager

---

MOD_PYTHON ERROR

ProcessId: 2637
Interpreter: 'TS1.unassigned-domain'

ServerName: 'TS1.unassigned-domain'
DocumentRoot: '/var/www/'

URI: '/sipprovision/admin'
Location: '/sipprovision/'
Directory: None
Filename: '/var/www/sipprovision/admin'
PathInfo:

Phase: 'PythonHandler'
Handler: 'django.core.handlers.modpython'

Traceback (most recent call last):

File "/usr/lib/python2.5/site-packages/mod_python/importer.py", line 1537, in HandlerDispatch

default=default_handler, arg=req, silent=hlist.silent)

File "/usr/lib/python2.5/site-packages/mod_python/importer.py", line 1229, in _process_target

result = _execute_target(config, req, object, arg)

File "/usr/lib/python2.5/site-packages/mod_python/importer.py", line 1128, in _execute_target

result = object(arg)

File "/usr/lib/python2.5/site-packages/django/core/handlers/modpython.py", line 228, in handler

return ModPythonHandler()(req)

File "/usr/lib/python2.5/site-packages/django/core/handlers/modpython.py", line 201, in call

response = self.get_response(request)

File "/usr/lib/python2.5/site-packages/django/core/handlers/base.py", line 67, in get_response

response = middleware_method(request)

File "/usr/lib/python2.5/site-packages/django/middleware/common.py", line 56, in process_request

if (not _is_valid_path(request.path_info) and

File "/usr/lib/python2.5/site-packages/django/middleware/common.py", line 142, in _is_valid_path

urlresolvers.resolve(path)

File "/usr/lib/python2.5/site-packages/django/core/urlresolvers.py", line 246, in resolve

return get_resolver(urlconf).resolve(path)

File "/usr/lib/python2.5/site-packages/django/core/urlresolvers.py", line 179, in resolve

for pattern in self.urlconf_module.urlpatterns:

File "/usr/lib/python2.5/site-packages/django/core/urlresolvers.py", line 198, in _get_urlconf_module

self._urlconf_module = import(self.urlconf_name, {}, {}, [])

File "/var/www/sipprovision/urls.py", line 2, in <module>

from extensions.models import Extension

File "/var/www/sipprovision/extensions/models.py", line 42, in <module>

class ExtensionForm(ModelForm):

File "/usr/lib/python2.5/site-packages/django/forms/models.py", line 195, in new

opts.exclude, formfield_callback)

File "/usr/lib/python2.5/site-packages/django/forms/models.py", line 162, in fields_for_model

formfield = formfield_callback(f)

File "/usr/lib/python2.5/site-packages/django/forms/models.py", line 177, in <lambda>

lambda f: f.formfield())

File "/usr/lib/python2.5/site-packages/django/db/models/fields/related.py", line 694, in formfield

'queryset': self.rel.to._default_manager.complex_filter(

AttributeError: 'str' object has no attribute '_default_manager'

---

from django.db import models
from sipconfig import *
from django.forms import ModelForm, fields, TextInput, IntegerField
# Create your models here.
class Plc(models.Model):

name=models.CharField(max_length=30)
ip_addr=models.IPAddressField()
ip_port=models.IntegerField(default=9600)
plc_net=models.IntegerField()
plc_node=models.IntegerField()
plc_unit=models.IntegerField()

def unicode(self):

return self.name

class Admin: pass

class VoipGateway(models.Model):

name=models.OneToOneField('sipconfig.station')
def unicode(self):

return self.name.dev_name

class Admin: pass

class Extension(models.Model):

PREFIX_CHOICE=(

('1','station'),
('9','lock'),
('8','voicemail'))

context=models.ForeignKey('sipconfig.station')
plc_sys=models.ForeignKey(Plc)
gateway=models.ForeignKey(VoipGateway)
word=models.IntegerField()
bit=models.IntegerField()
prefix=models.CharField(max_length=2,choices=PREFIX_CHOICE)
ph_number=models.CharField(max_length=8)

def unicode(self):

return self.context.dev_name +'-'+ self.ph_number

class Admin: pass

class ExtensionForm(ModelForm):

class Meta:

model = Extension

class ExtAddToContextForm(ModelForm):

word_increment=IntegerField(widget=TextInput,initial=0)
bit_increment=IntegerField(widget=TextInput,initial=0)
phone_increment = IntegerField(widget=TextInput,initial=0)
class Meta:

model = Extension

class PlcForm(ModelForm):

class Meta:

model=Plc

class VoipGatewayForm(ModelForm):

class Meta:

model=VoipGateway

---

from sipprovision.extensions.models import Plc,VoipGateway,Extension
from django.contrib import admin
class ExtensionAdmin(admin.ModelAdmin):

list_display=('context','plc_sys','gateway','word','bit','prefix','ph_number')
list_filter=('plc_sys','prefix')

class PlcAdmin(admin.ModelAdmin):

list_display=('name','ip_addr','ip_port','plc_node','plc_net','plc_unit')

admin.site.register(Plc,PlcAdmin)
admin.site.register(VoipGateway)
admin.site.register(Extension,ExtensionAdmin)

---

def formfield(self, kwargs):

defaults = {

'form_class': forms.ModelChoiceField,
'queryset': self.rel.to._default_manager.complex_filter(

self.rel.limit_choices_to),

'to_field_name': self.rel.field_name,

}
defaults.update(kwargs)
return super(ForeignKey, self).formfield(defaults)