Problem importing files in Django settings.py

Question

I have a Django project which seemed to work pretty well with settings.py, which also imported a local_settings.py without problem. I've now added the following lines at the end of the settings file : ``` try: from extras import * except ImportError, e: print "import extras failed :: " + `e` ``` extras.py is a file of extra configuration information sitting in the same directory as settings.py and local_settings.py, however, I'm now getting : ``` import extras failed :: ImportError('Settings cannot be imported, because environment variable DJANGO_SETTINGS_MODULE is undefined.',) ``` This seems to be due to me trying to ``` from django.contrib.auth.models import User,UserManager from django.db import models ``` in that extras.py file. Anyone have any ideas? cheers

Accepted Answer

Typically, having a line like

```
from django.db import models
```

in `settings.py` will lead to a circular dependency. This causes an import error, which gets reported slightly differently in different versions of Django. For example, if I add that line to a working Django setup and invoke "manage.py shell", I get:

Error: Can't find the file 'settings.py' in the directory containing './manage.py'. It appears you've customized things. You'll have to run django-admin.py, passing it your settings module. (If the file settings.py does indeed exist, it's causing an ImportError somehow.)

If I remove that line, everything's fine again.

The reason is that Django's model loading machinery (located in the `django.db.models` package) imports `settings.py`, reads its `INSTALLED_APPS` to see what apps should be installed, and then loads those apps. (You can confirm this by adding a print statement to `__init__.py` for one of your installed apps.)

If you try to import `django.db` stuff in `settings.py`, that will lead to a circular import dependency and an `ImportError`-related error message.

One workaround is to move the functionality which requires the problematic imports (and the imports themselves) to an app.

Problem importing files in Django settings.py

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