###############
# Urls in /home/bux/Projets/djStock/stock/urls.py
from django.conf.urls.defaults import *

urlpatterns = patterns('',
  [...]
  url(r'factory/view/(?P<factory_id>[0-9]+)$', 'stock.views.factory.view', name='factory_view'),
)

###############
# View in /home/bux/Projets/djStock/stock/views/factory.py
[...]
from djStock.stock.models import ProductFactory

[...]
def view(request, factory_id):
  factory = ProductFactory.objects.get(pk=factory_id)
  factory.products.all()

###############
# Models in /home/bux/Projets/djStock/stock/models/XxXxx.py

from stock.lib.ModelObject import ModelObject
from django.db.models import Model
from stock.models.Product import Product
from django.db import models
from stock.managers.models.filters.ProductFactoryFilter import ProductFactoryFilter as Filter
from django.utils.translation import ugettext_lazy as _


class ProductFactory(Model):

  objects = models.Manager()
  filter = Filter()

  name = models.CharField(_(u"Name"), max_length=128)
  products = models.ManyToManyField(Product, through='ProductFactoryProduct')
  components = models.ManyToManyField(Product, through='ProductFactoryComponent')

  def produceds_string(self):
    return ", ".join([product.name for product in self.products.all()])
    #return ", ".join([product.quantity + ' ' + product.name for product in self.products])

  def components_string(self):
    return ", ".join([product.name for product in self.components.all()])
    #return ", ".join([product.quantity + ' ' + product.name for product in self.components])

  def __str__(self):
    return self.name

  class Meta:
    app_label = 'stock'


# other file with model
from stock.lib.ModelObject import ModelObject
#from stock.models.ProductFactory import ProductFactory
#from stock.models.Product import Product
from django.db import models
from django.utils.translation import ugettext_lazy as _


class ProductFactoryProduct(ModelObject):

  factory = models.ForeignKey('ProductFactory')
  product = models.ForeignKey('Product')
  quantity = models.IntegerField(_(u"Quantity"), default=1)

  class Meta:
    app_label = 'stock'

# other file with model
from stock.lib.ModelObject import ModelObject
#from stock.models.ProductFactory import ProductFactory
#from stock.models.Product import Product
from django.db import models
from django.utils.translation import ugettext_lazy as _


class ProductFactoryComponent(ModelObject):

  factory = models.ForeignKey('ProductFactory')
  product = models.ForeignKey('Product')
  quantity = models.IntegerField(_(u"Quantity"), default=1)

  class Meta:
    app_label = 'stock'

# other file with model
from django.db import models
from stock.lib.ModelObject import ModelObject
from django.utils.translation import ugettext_lazy as _
from stock.tools.array import get_string_in_tuples_choices
from stock.models import Article
from django.db.models import Count
from stock.managers.models.filters.ProductFilter import ProductFilter as Filter
from stock.lib.exceptions import DeleteIntegrityException, ExistingWaitingPurchaseException
from stock.managers.objects.ActiveObjects import ActiveObjects
from Purchase import Purchase
from stock.lib.forms.validators import internal_code_is_unique_all, barcode_is_unique_product
from ProductReference import ProductReference


class Product(ModelObject):

  CONSUMTION_DIRECT = 'd'
  CONSUMTION_INDIRECT = 'i'

  CONSUMTION_TYPES = (
    (CONSUMTION_DIRECT, _(u"Direct")),
    (CONSUMTION_INDIRECT, _(u"Indirect"))
  )

  WORK_UNIT_CM = 'cm'
  WORK_UNIT_M = 'm'
  WORK_UNIT_L = 'l'
  WORK_UNIT_KG = 'kg'
  WORK_UNIT_UNIT = 'un'
  WORK_UNIT_FLASK = 'fl'
  WORK_UNIT_BOX = 'bo'
  WORK_UNIT_EMPTY = 'na'

  WORK_UNITS = (
    (WORK_UNIT_CM, _(u"Centimeter")),
    (WORK_UNIT_M, _(u"Meter")),
    (WORK_UNIT_L, _(u"Liter")),
    (WORK_UNIT_KG, _(u"Kilograme")),
    (WORK_UNIT_UNIT, _(u"Unit")),
    (WORK_UNIT_FLASK, _(u"Flacon")),
    (WORK_UNIT_BOX, _(u"Boite")),
    (WORK_UNIT_EMPTY, _(u"None")),
  )

  name = models.CharField(_(u"Designation"), max_length=128)
  packaging = models.IntegerField(_(u"Packaging"), default=1)
  comsumtion_type = models.CharField(max_length=1,
                                     choices=CONSUMTION_TYPES,
                                     default=CONSUMTION_DIRECT)
  work_unit = models.CharField(max_length=2,
                                     choices=WORK_UNITS,
                                     default=WORK_UNIT_EMPTY)
  brand = models.CharField(_(u"Brand"), max_length=32, blank=True)
  categorys = models.ManyToManyField('ProductCategory', db_table="stock_product_category_rel", blank=True, null=True)
  providers = models.ManyToManyField('Provider', through='ProductReference')
  quantity = models.IntegerField(_(u"Quantity"), default=0)
  quantity_with_ampute = models.IntegerField(_(u"Quantity with consumeds"), default=0)
  active = models.BooleanField(_(u"Active"), default=True)
  stock_limit = models.IntegerField(_(u"Stock limit"), default=0)
  purchase_quantity = models.IntegerField(_(u"Standart purchase quantity"), default=None, blank=True, null=True)
  code = models.CharField(_(u"Internal code"), max_length=32, blank=True, null=True)
  barcode = models.CharField(_(u"Barcode"), max_length=32, blank=True, null=True)

  objects = models.Manager()
  active_objects = ActiveObjects()
  filter = Filter()

  def delete(self):
    if self.bypass_integrity:
      super(Product, self).delete()
    else:
      if Purchase.objects.filter(complete=False, references__product=self).count():
        raise ExistingWaitingPurchaseException(_("You can't delete this Product: Purchase not complete containing this product"))
      self.active = False
      self.save()

  def __unicode__(self):
    return self.name

  def providers_string(self):
    return ", ".join(self.get_providers_names())

  def get_providers_names(self):
    providers_names = []
    for product_reference in ProductReference.objects.filter(product=self):
      providers_names.append(product_reference.provider.name)
    return providers_names

  def is_direct_consumtion(self):
    if self.comsumtion_type == self.CONSUMTION_DIRECT:
      return True
    return False

  def is_indirect_consumtion(self):
    if self.comsumtion_type == self.CONSUMTION_INDIRECT:
      return True
    return False

  def consumtion_type_string(self):
    return get_string_in_tuples_choices(self.CONSUMTION_TYPES, self.comsumtion_type)

  def work_unit_string(self):
    return get_string_in_tuples_choices(self.WORK_UNITS, self.work_unit)

  def quantity_and_ampute(self):
    if not self.is_direct_consumtion() and self.quantity != self.quantity_with_ampute:
      return True
    return False

  def quantity_string(self):
    if self.quantity_and_ampute():
      return "%d (%d)" % (self.quantity, self.quantity_with_ampute)
    return self.quantity

  def get_articles_ampute(self):
    return Article.objects.values('packaging')\
                          .filter(product=self)\
                          .exclude(packaging=self.packaging)\
                          .annotate(pcount=Count('packaging'))\
                          .order_by('-pcount')

  def stock_is_under_limit(self):
    if self.quantity_and_ampute():
      return True if self.quantity_with_ampute <= self.stock_limit else False
    return True if self.quantity <= self.stock_limit else False

  def get_bundles_codes(self):
    bundles = []
    articles_records = Article.objects.values('bundle').filter(product=self).distinct()
    for article_record in articles_records:
      bundles.append(article_record['bundle'])
    return bundles

  def get_bundles_codes_string(self):
    return ", ".join([bundle for bundle in self.get_bundles_codes() if bundle])

  def get_bundle_quantitys(self, bundle):
    return Article.objects.filter(product=self, bundle=bundle).count()

  def data(self):
    return {
      'name': self.name,
      'packaging': self.packaging,
      'work_unit': self.work_unit,
      'brand': self.brand
    }

  def validate_unique(self, *args, **kwargs):
    super(Product, self).validate_unique(*args, **kwargs)
    internal_code_is_unique_all(self)
    barcode_is_unique_product(self)

  @staticmethod
  def pre_delete(**kwargs):
    if not kwargs.get('instance').bypass_integrity:
      raise DeleteIntegrityException(kwargs.get('instance'))

#   @staticmethod
#   def pre_save(**kwargs):
#     # (raw) not applicable when fixture
#     if not kwargs.get('raw'):
#       if kwargs.get('instance').id:
#         check_forbidden_update_fields(Product.objects.get(pk=kwargs.get('instance').id), kwargs.get('instance'),\
#                                       ('packaging', 'comsumtion_type', 'work_unit', 'brand'))

  class Meta:
    app_label = 'stock'
    ordering = ('name',)

############
# Full trace

Internal Server Error: /stock/factory/view/1
Traceback (most recent call last):
  File "/home/bux/.virtualenvs/djstock/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 115, in get_response
    response = callback(request, *callback_args, **callback_kwargs)
  File "/home/bux/Projets/djStock/stock/views/factory.py", line 64, in view
    factory.products.all()
  File "/home/bux/.virtualenvs/djstock/local/lib/python2.7/site-packages/django/db/models/manager.py", line 128, in all
    return self.get_query_set()
  File "/home/bux/.virtualenvs/djstock/local/lib/python2.7/site-packages/django/db/models/fields/related.py", line 615, in get_query_set
    return super(ManyRelatedManager, self).get_query_set().using(db)._next_is_sticky().filter(**self.core_filters)
  File "/home/bux/.virtualenvs/djstock/local/lib/python2.7/site-packages/django/db/models/query.py", line 669, in filter
    return self._filter_or_exclude(False, *args, **kwargs)
  File "/home/bux/.virtualenvs/djstock/local/lib/python2.7/site-packages/django/db/models/query.py", line 687, in _filter_or_exclude
    clone.query.add_q(Q(*args, **kwargs))
  File "/home/bux/.virtualenvs/djstock/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1271, in add_q
    can_reuse=used_aliases, force_having=force_having)
  File "/home/bux/.virtualenvs/djstock/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1139, in add_filter
    process_extras=process_extras)
  File "/home/bux/.virtualenvs/djstock/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1337, in setup_joins
    "Choices are: %s" % (name, ", ".join(names)))
FieldError: Cannot resolve keyword 'productfactory' into field. Choices are: active, article, barcode, brand, categorys, code, comsumtion_type, id, name, packaging, productreference, provider, providers, purchase_quantity, quantity, quantity_with_ampute, stock_limit, stockmovement, stockmovementproduct, work_unit