Saturday, June 09, 2012

How To use Sphinx Autodoc on ReadTheDocs with a Django application

Sphinx is awesome for writing documentation. ReadTheDocs is awesome for hosting it. Autodocs are great for covering your entire API easily. Django is a great framework that makes my job easier.

Between these four things is an interaction that only brought me pain, however. I'm here to help the next dev avoid this.

Autodocs works by importing your modules and walking over the classes and functions to build documentation out of the existing docstrings. It can be used to generate complete API docs quickly and keep them in sync with the libraries existing docstrings, so you won't get conflicts between your docs and your code. Fantastic.

This creates a problem when used with Django applications, where many things cannot be imported unless a valid settings module can be found. This can prevent a hurdle in some situations, and requires a little boilerplate to get working properly with Sphinx. It require a little extra to get working on ReadTheDocs. What makes this particularly hard to figure out, is the environment running on their servers is not the same as your own, and you have only terse error reports to guess about.

Here is the snippet you need to add into the of your docs/ to tell Sphinx how to load a

import sys, os

import django 

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "settings")
if django.VERSION < (1, 4):
    from import setup_environ

    settings = __import__(os.environ["DJANGO_SETTINGS_MODULE"])

and a simple is all you need sitting beside that.

# Django settings for docs project.
# import source code dir
import os
import sys
sys.path.insert(0, os.getcwd())
sys.path.insert(0, os.path.join(os.getcwd(), os.pardir))

SITE_ID = 303
DEBUG = True

DATABASES = {"default": {

    "NAME": ":memory:",
    "ENGINE": "django.db.backends.sqlite3",
    "USER": '',
    "PASSWORD": '',
    "PORT": '',


    'YOUR_APP_HERE', # This is where you put your app

And you should be good to go!


Anentropic said...

I'm not quite clear from this... do you propose a structure like:


i.e. a separate just for your docs/ dir that points up at the main django root?

I guess you still need to go through and add ..automodule directives to the rst index for all your INSTALLED_APPS ?

Sorry for dumb questions, first time I've used Sphinx...

Calvin Spealman said...


Yes, you've got it right.

Usually a project has lots of settings anyway. Local dev settings, staging, production, different settings for celery workers, etc. Docs is just one more context you need some settings for.

Alex Little said...

Thanks for posting this - it really helped me out - I was struggling to resolve the errors about Django settings in the ReadTheDocs build output.

I write here about programming, how to program better, things I think are neat and are related to programming. I might write other things at my personal website.

I am happily employed by the excellent Caktus Group, located in beautiful and friendly Carrboro, NC, where I work with Python, Django, and Javascript.