> Den 1. sep. 2016 kl. 20.14 skrev Stodge <sto...@gmail.com>:
> 
> I have two models, Volume and Group. The Volume model has a foreign key to 
> Group.
> 
> When a user deletes a Volume the post_delete signal handler sends an HTTP 
> DELETE request (/volume) to another server process. This works great. 
> However, when the user deletes a Group, the cascading delete also deletes all 
> volumes in that group. That means I get lots (I'm talking <100) of 
> post_delete signals for the Volume model and therefore lots of HTTP requests.
> 
> Is there anyway to avoid this? Ideally, I'd like to send the HTTP DELETE  
> request (/volume) when a volume is deleted, but send a different HTTP DELETE 
> request (/group) when the group is deleted and avoid sending any volume HTTP 
> DELETE requests.

You could disconnect the post_delete signal for Volume temporarily, but that's 
a hack.

You probably have to abandon signals on the Volume model. I would attach the 
post_delete signals logic directly to the Volume.delete() method and add an 
option to disable signaling:

class Volume(models.Model):
    [....]
    def my_signal_logic(self):
        do_whatever()

    def delete(self, *args, **kwargs):
       with_signal = kwargs.pop('signal', True)
       if with_signal:
           self.my_signal_logic()
       super().delete(*args, **kwargs)
           

Then in the post_delete signal for Group, you delete the Volumes explicitly, 
telling delete() not to signal:

    for v in instance.volumes.all():
        v.delete(signal=False)

    requests.delete('/group/%s' % instance.pk)


Erik

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