Re: Misfiring signal handler

If you can create a self-contained small example project which does
this, it would make it much easier to debug this. I don't know why the
signal misfired, and I don't see a way that it could misfire. So,
without some ability to reproduce this it is hard to help.

- Anssi

On Dec 30, 5:40 pm, Jay Wineinger <jay.winein...@gmail.com> wrote:
> Hey guys,
>
> I have an odd problem where a post_save signal handler is getting
> called from a class different than what I specified as the sender.
> The code is athttp://dpaste.com/hold/679348/and also below for when
> the pastebin is deleted.
>
> I'm connecting the rating_denormalizer() function to the post_save
> signal of the Rating model.  However, when I visit the site with a
> fresh browser a new Session is created and for some reason, this
> signal handler is called with a Session instance.
>
> I was able to fix this by moving this code from users/signals.py to
> bars/signals.py, directly importing Rating instead of using get_model,
> and moving the AppUser import inside rating_denormalizer().  However,
> I still would like to figure out why this was happening.
>
> # users/signals.py
> from django.db.models.signals import post_save
> from django.db.models import F, get_model
>
> Rating = get_model('bars','Rating')
> AppUser = get_model('users','AppUser')
>
> def rating_denormalizer(sender, instance, created, **kwargs):
>     """
>     Post-save signal handler on Rating to keep the denormalized fields
> on
>     AppUser up-to-date
>     """
>     if created:
>         AppUser.objects.filter(pk=instance.user_id).update(
>             rating_count=F('rating_count') + 1,
>             last_rating=instance.created,
>         )
> post_save.connect(rating_denormalizer, sender=Rating,
> dispatch_uid='rating_denormalizer')
>
> # Get a 500 error when going to /admin/ with a fresh browser
> 2011-12-27 16:45:07,608 ERROR Internal Server Error: /admin/
> Traceback (most recent call last):
>   File "/var/www/python/myapp/lib/python2.6/site-packages/django/core/
> handlers/base.py", line 178, in get_response
>     response = middleware_method(request, response)
>   File "/var/www/python/myapp/lib/python2.6/site-packages/django/
> contrib/sessions/middleware.py", line 36, in process_response
>     request.session.save()
>   File "/var/www/python/myapp/lib/python2.6/site-packages/django/
> contrib/sessions/backends/db.py", line 63, in save
>     obj.save(force_insert=must_create, using=using)
>   File "/var/www/python/myapp/lib/python2.6/site-packages/django/db/
> models/base.py", line 460, in save
>     self.save_base(using=using, force_insert=force_insert,
> force_update=force_update)
>   File "/var/www/python/myapp/lib/python2.6/site-packages/django/db/
> models/base.py", line 570, in save_base
>     created=(not record_exists), raw=raw, using=using)
>   File "/var/www/python/myapp/lib/python2.6/site-packages/django/
> dispatch/dispatcher.py", line 172, in send
>     response = receiver(signal=self, sender=sender, **named)
>   File "/var/www/python/myapp/App/users/signals.py", line 13, in
> rating_denormalizer
>     AppUser.objects.filter(pk=instance.user_id).update(
> AttributeError: 'Session' object has no attribute 'user_id'

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