migration chicken-egg problem

[stefanfoulis]

Can't run python manage.py migrate on a fresh database, because multisite.template.loaders.filesystem causes a db query to the django_site table.

[stefanfoulis]

The workaround is of course to remove the template loader at initial migration time. But in some automated environments that is tedious.

IMHO no db queries or cache access should happen at import time.

[jedie]

I get the same problem :(

But removing the template loader will not help here.

[mghughes]

I can't seem to reproduce this problem - using a fresh django 1.9 project with django-multisite 1.3.1 and these settings: https://gist.github.com/mghughes/6710f72d5c6ad6ffb6e4c9857ced7fe3

Since there are multiple people with this problem, am I missing something obvious? Or can you provide more information about what you're doing differently?

[JordanReiter]

Stepping in because I've run across this error now.

This error can occur if you use an app which attempts to load a template on startup. I'm not sure how many apps do this regularly, but one prominent one is django-cms. It happens when it calls setup() in its apps.py file. This in turn calls plugin_pool.validate_templates() which calls loader.get_template().

There is no way to prevent this error from occurring as far as I can tell. I've looked at all of the involved code and apart from setting django-cms to catch all exceptions in its validate_templates method there isn't a way of preventing the error.

Obviously, this means that doing a standard test which starts with a completely empty database will not work unless you disable multisite during testing.

One possibility is something like this (untested):

# settings.py
_, command = sys.argv[:2]
if command in ['test', 'migrate']:
    ORIGINAL_TEMPLATES = list(TEMPLATES)
    TEMPLATES[0]['loaders'].remove('multisite.template_loader.Loader')

And then, in a test file:

from django.conf import settings

class TestMultiSiteLayouts(TestCase):
    def test_something:
        with self.override_settings(TEMPLATES=list(settings.ORIGINAL_TEMPLATES)):
            … do tests for multisite here …