Why does Django development version not know where my packages are?

Question

I used to be developing a Django app using a stable version (1.6) of Django I got installed on Ubuntu using sudo apt-get install python-django, and I also used the Django packages sorl-thumbnail and tastypie.

I have since wanted to switch to using Django's development version, and so I installed it with the instructions in their documentation:

1. git clone git://github.com/django/django.git django-trunk
2. sudo pip install -e django-trunk/

On my machine, Django is now located in ~/git/django-trunk.

However, when I go back to my Django project directory and run python manage.py syncdb I seem to get:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/$USER/git/django-trunk/django/core/management/__init__.py", line 427, in execute_from_command_line
    utility.execute()
  File "/home/$USER/git/django-trunk/django/core/management/__init__.py", line 391, in execute
    django.setup()
  File "/home/$USER/git/django-trunk/django/__init__.py", line 21, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/$USER/git/django-trunk/django/apps/registry.py", line 84, in populate
    app_config = AppConfig.create(entry)
  File "/home/$USER/git/django-trunk/django/apps/base.py", line 86, in create
    "cannot import name '%s' from '%s'" % (cls_name, mod_path))
ImportError: cannot import name 'thumbnail' from 'sorl'

Is this because Django no longer knows where my installed Django apps are?

I think they are in /usr/local/lib/python2.7/dist-packages if that helps...

How do I fix this error and get all my Django apps to work with the development version? Did I simply need to git clone the Django development version into /usr/local/lib/python2.7/dist-packages, or something else?

Any help would be greatly appreciated, thank you so much in advance!

Answer 1

You need to use a virtual environment, and install the dependencies for your project in each virtual environment.

This way, the Python interpreter will have access to the required libraries at all times. To get started:

sudo apt-get install -y python-virtualenv

This will install any required libraries to make virtualenv work; then for each project you start by creating a fresh virtual environment. All these commands are run as your normal user (without sudo):

$ virtualenv django_env
$ source django_env/bin/activate
(django_env) $ pip install django tastypie solr-thumbnail

Typing activate will activate the enviornment, so your shell will point to the correct versions of Python. You'll note the (django_env) which indicates the environment is currently active.

From this point on, anything you install will be installed only in this virtual environment. Once you are finished working, typing deactivate will return you back to the system Python environment:

(django_env) $ deactivate
$