django filer - ImportError: cannot import name mixins - django-cms

Question

I have a django 1.4 installation and I have django-cms running.
I'm try to install filer but when I syncdb or runserver I keep having this error.
from filer.models import mixins
ImportError: cannot import name mixins
In my setting.py I have:
INSTALLED_APPS = (
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
'django.contrib.messages',
'django.contrib.staticfiles',
# Uncomment the next line to enable the admin:
'django.contrib.admin',
'cms',
'mptt',
'menus',
'south',
'sekizai',
'ftlom',
#'cms.plugins.text',
#'cms.plugins.picture',
'cmsplugin_twitter',
'easy_thumbnails',
'filer',
#'ordered_model',
#'cmsplugin_filer_file',
#'cmsplugin_filer_folder',
'cmsplugin_filer_image',
#'cmsplugin_gallery',
'cms.plugins.video',
#'gunicorn',
# Uncomment the next line to enable admin documentation:
# 'django.contrib.admindocs',
)
If I remove filer and all its plugins my site works fine. What could possibly cause the problem? thanks
Traceback :
Validating models...
Unhandled exception in thread started by <bound method Command.inner_run of <django.contrib.staticfiles.management.commands.runserver.Command object at 0x1050d4fd0>>
Traceback (most recent call last):
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site- packages/django/core/management/commands/runserver.py", line 91, in inner_run
self.validate(display_num_errors=True)
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site-packages/django/core/management/base.py", line 266, in validate
num_errors = get_validation_errors(s, app)
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site-packages/django/core/management/validation.py", line 30, in get_validation_errors
for (app_name, error) in get_app_errors().items():
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site-packages/django/db/models/loading.py", line 158, in get_app_errors
self._populate()
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site-packages/django/db/models/loading.py", line 67, in _populate
self.load_app(app_name)
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site-packages/django/db/models/loading.py", line 88, in load_app
models = import_module('.models', app_name)
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site-packages/django/utils/importlib.py", line 35, in import_module
__import__(name)
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site-packages/filer/models/__init__.py", line 2, in <module>
from filer.models.clipboardmodels import *
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site-packages/filer/models/clipboardmodels.py", line 5, in <module>
from filer.models import filemodels
File "/Users/Alex/.virtualenvs/FTLOM/lib/python2.7/site-packages/filer/models/filemodels.py", line 8, in <module>
from filer.models import mixins
ImportError: cannot import name mixins
This my pip freeze :
Django==1.4
PIL==1.1.7
South==0.8.1
cmsplugin-filer==0.9.5
cmsplugin-twitter==1.0.4
django-classy-tags==0.4
django-cms==2.4.1
django-filer==0.9.3
django-mixins==0.0.10
django-mptt==0.5.2
django-ordered-model==0.2.0
django-polymorphic==0.5
django-sekizai==0.7
easy-thumbnails==1.3
gunicorn==17.5
html5lib==1.0b1
six==1.3.0
wsgiref==0.1.2

Answer 1

You are running Django version 1.4.1 or lower, which you can check by any of these methods:
on the bash
pip freeze | grep Django | awk 'BEGIN { FS = "==" } ; { print $2 }'
on the bash, if django has been properly set to the Linux path
django-admin --version
on the django.shell
import django
django.VERSION #or
django.get_version()
Although not specifically asserted, it seems that django-filer 0.9.x is incompatible with django versions below 1.4.1
Fixing the mixin problem won't help:
First off, django-mixins is a different project, and its namespace not used nor conflicting.
django-filer contains a module mixins, which is more of a stump for Icon-loading at the moment, rather than anything of genuine importance.
You could change the foldermodels.py and filemodels.py:
from filer.models import mixins
=> to
import filer.models.mixins
Yet after resolving the mixinsissue, you will still struggle with import difficulties of django.utils.six
Part of the reason is that utils.six, a Python 2/3 compatibility layer has only recently been added to Django 1.4.2
Solution
You can see from https://github.com/stefanfoulis/django-filer/blob/develop/HISTORY , that installing version 0.8.7 could work. First remove the newer django-filer package though.
pip uninstall django-filer
easy_install django-filer==0.8.7
Indeed this version works well on Django version 1.4.1
Note: If you installed django-mixins by mistake, remove it as well. It is good practice to not keep unused and non-dependent django-modules around.

Answer 2

I ran into the same problem. The problem was hard to find but simple to solve.
After installing django-polymorphic, everything worked fine.