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comparison weblinks/signals.py @ 581:ee87ea74d46b

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For Django 1.4, rearranged project structure for new manage.py.
author Brian Neal <bgneal@gmail.com>
date Sat, 05 May 2012 17:10:48 -0500
parents gpp/weblinks/signals.py@3a4bbf9c2cce
children
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580:c525f3e0b5d0 581:ee87ea74d46b
1 """Signals for the weblinks application.
2 We use signals to compute the denormalized category counts whenever a weblink
3 is saved."""
4 from django.db.models.signals import post_save
5 from django.db.models.signals import post_delete
6
7 from weblinks.models import Category, Link
8
9
10 def on_link_save(sender, **kwargs):
11 """This function updates the count field for all categories.
12 It is called whenever a link is saved via a signal.
13 """
14 if kwargs['created']:
15 # we only have to update the parent category
16 link = kwargs['instance']
17 cat = link.category
18 cat.count = Link.public_objects.filter(category=cat).count()
19 cat.save()
20 else:
21 # update all categories just to be safe (an existing link could
22 # have been moved from one category to another
23 cats = Category.objects.all()
24 for cat in cats:
25 cat.count = Link.public_objects.filter(category=cat).count()
26 cat.save()
27
28
29 def on_link_delete(sender, **kwargs):
30 """This function updates the count field for the link's parent
31 category. It is called when a link is deleted via a signal.
32 """
33 # update the parent category
34 link = kwargs['instance']
35 cat = link.category
36 cat.count = Link.public_objects.filter(category=cat).count()
37 cat.save()
38
39
40 post_save.connect(on_link_save, sender=Link, dispatch_uid='weblinks.signals')
41 post_delete.connect(on_link_delete, sender=Link, dispatch_uid='weblinks.signals')