Dealing with multiple Django versions

More than a few Django websites I built in the past two years are still live and active. And because they were made at different times, they were built against different Django versions.

If a (virtual) web host accidentally imports a different version of django, the site will completely break at best... or exhibit subtle, hard-to-discover runtime errors at worst. Guard against this by placing a version check in settings.py:

from django import VERSION as DJANGO_VERSION
assert (1,1) == DJANGO_VERSION[:2], DJANGO_VERSION

(If, for example, this web site is built for version 1.1. Change the tuple in the assert statement to match whatever version is required.)

This will cause the host start-up to immediately fail, loudly and visibly, if the incorrect Django version has been imported.