Question

I have a tuple, INSTALLED_APPS, and I want to merge extra items into it to get my local apps in the tuple too without altering the main settings file. I came this far:

DEFAULT_APPS = list(INSTALLED_APPS)
MY_APPS_LIST = DEFAULT_APPS.append('south')

however if I try to convert this into a tuple again by running:

INSTALLED_APPS = tuple(MY_APPS_LIST)

I get:

TypeError: 'NoneType' object is not iterable

The question is rather fundamental I’d say, but I can’t really find “the” method for this, or even any method that works for me at all… I did find that both list() and tuple() in the Django shell return an empty object of that type, so I don’t understand where the TypeError might be coming from…

Help appreciated!

Answer 1

append doesn’t return a new list — it modifies the original list, returning None. You want MY_APPS_LIST = DEFAULT_APPS + ['south']