Django: custom middleware called twice

Question

I have a custom middleware which is called twice for every request and I don't understand why. This is my middleware:

class MyMiddleWare(object):

  def process_request(self, request):
    print 'FOO'
    return None

This is my middleware setting:

MIDDLEWARE_CLASSES = (
    'django.middleware.common.CommonMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.locale.LocaleMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'MyMiddleware',
)

And this is the output in the console after homepage request:

[28/Jun/2013 19:48:26] FOO
[28/Jun/2013 19:48:26] "GET / HTTP/1.1" 200 7468
[28/Jun/2013 19:48:27] FOO

I tried to comment out all the other middlewares and the problem is the same. What should I do?

ps: the described behavior is replicable in each view

UPDATE:

I tried to implement process_view rather than process_request and it is called once as expected... why?

UPDATE 2:

process_response is called twice like process_request

UDATE 3:

ooooh shiiiit! It's a request to favicon.ico (which I haven't defined myself)... who is calling this file?

It calls it once per request type. Is there an ajax request in the page ? — karthikr, Jun 28 '13 at 20:06
Sure it's only one request and you're probably not serving static files through `runserver` or something like that? — Bernhard Vallant, Jun 28 '13 at 20:07
I'm using the development server without reload, and there is no ajax request... I tried to implement process_view rather than process_request and it is called once as expected... I don't understand :/ — daveoncode, Jun 28 '13 at 20:13
damned browser! ...I created a dummy favicon and now the middleware is called only once as expected :) — daveoncode, Jun 28 '13 at 21:13
@daveoncode You should submit your own answer to this question for good housekeeping if you have the time to. — Farmer Joe, Mar 07 '14 at 14:28

daveoncode · Accepted Answer · 2014-03-22T18:15:59.220

11

The problem is that if you serve favicon.ico by defining it as django url (like the code below):

(r'^favicon\.ico$',
  'django.views.generic.simple.redirect_to',
  {'url': settings.MEDIA_URL+'images/favicon.ico'}),

All your middleware get called twice: 1 time for the page you have requested + 1 time for the favicon (which is always called by the browser). The solution is simple: don't use django urls to serve your vaficon, instead put something like:

<link rel="icon" type="image/png" href="{% static 'core/img/favicon.ico' %}" />

in the <head> of your base template!

edited Mar 22 '14 at 18:15

answered Mar 07 '14 at 14:38

daveoncode

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1

This is not the only error source. jsi18n urls can be an issue too. – beruic Dec 06 '16 at 10:30

score 1 · Answer 2 · answered Mar 23 '16 at 22:39

1

Better solution is to add condition into your middlevare function that filters all serve functions.

if view_func.__name__ != 'serve':

answered Mar 23 '16 at 22:39

Honza Kremeň

11
1

What is `view_func`? Could you elaborate? There is no `view_func` in the `WSGIRequest` object we get on the middleware. – waqasgard Aug 14 '20 at 09:35

Django: custom middleware called twice

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