Fix Python – Execute code when Django starts ONCE only?

Question

Asked By – Bob_94

I’m writing a Django Middleware class that I want to execute only once at startup, to initialise some other arbritary code. I’ve followed the very nice solution posted by sdolan here, but the “Hello” message is output to the terminal twice. E.g.

from django.core.exceptions import MiddlewareNotUsed
from django.conf import settings

class StartupMiddleware(object):
    def __init__(self):
        print "Hello world"
        raise MiddlewareNotUsed('Startup complete')

and in my Django settings file, I’ve got the class included in the MIDDLEWARE_CLASSES list.

But when I run Django using runserver and request a page, I get in the terminal

Django version 1.3, using settings 'config.server'
Development server is running at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
Hello world
[22/Jul/2011 15:54:36] "GET / HTTP/1.1" 200 698
Hello world
[22/Jul/2011 15:54:36] "GET /static/css/base.css HTTP/1.1" 200 0

Any ideas why “Hello world” is printed twice? Thanks.

Now we will see solution for issue: Execute code when Django starts ONCE only?


Answer

Update from Pykler’s answer below: Django 1.7 now has a hook for this


Don’t do it this way.

You don’t want “middleware” for a one-time startup thing.

You want to execute code in the top-level urls.py. That module is imported and executed once.

urls.py

from django.confs.urls.defaults import *
from my_app import one_time_startup

urlpatterns = ...

one_time_startup()

This question is answered By – S.Lott

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