Why is writing my own MiddleWare crashing my Django application?

Question

I want to run a function before any view in my app is loaded, so I wrote my own middleware. It is in a file called "DoBeforeMiddleWare.py" located in the folder "my_app_name" and, for now, looks like

class DoBeforeMiddleWare:
    def process_request(self, request):
        return None
    def process_view(self, request, view_func, view_args, view_kwargs):
        return None

I try to place this function in my list of middleware in settings.py:

MIDDLEWARE_CLASSES = (
    'django.middleware.common.CommonMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'my_project_name.my_app_name.DoBeforeMiddleWare',
)

However, my app never loads after I restart passenger. Why? My app loads if I comment out the last line of |MIDDLEWARE_CLASSES|.

cberner · Answer 1 · 2012-04-22T00:10:33.697

1

process_request and process_view must return None or an HttpResponse object (reference). If you want a no-op middleware, you should change them to return None, as follows:

class DoBeforeMiddleWare:
    def process_request(self, request):
        return None
    def process_view(self, request, view_func, view_args, view_kwargs)
        return None

edited Apr 22 '12 at 00:10

answered Apr 21 '12 at 23:45

cberner

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Hmm, thanks but changing `class DoBeforeMiddleWare(request):` to `class DoBeforeMiddleWare(object):` is still stalling my application. – dangerChihuahua007 Apr 21 '12 at 23:52
Revised my answer to include another issue with your class – cberner Apr 22 '12 at 00:00
Thanks, I updated my question (above), but I think the app is still stalling. – dangerChihuahua007 Apr 22 '12 at 00:06
Updated my answer again :) You need to return None from process_request and process_view. – cberner Apr 22 '12 at 00:11
Thanks, but the updated version above strangely doesn't work either :( Is it because I'm accessing the middleware incorrectly? – dangerChihuahua007 Apr 22 '12 at 00:22
1

Hmm. You might try removing my_project_name from the import. I always just use the app name. Can't think of much else though – cberner Apr 22 '12 at 00:29

Why is writing my own MiddleWare crashing my Django application?

1 Answers1