Mercurial > public > sg101
comparison gpp/weblinks/signals.py @ 202:7aa061ed387c
Should have added signals.py in r204.
| author | Brian Neal <bgneal@gmail.com> |
|---|---|
| date | Wed, 28 Apr 2010 02:58:07 +0000 |
| parents | |
| children | 3a4bbf9c2cce |
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| 201:bc958bc3c6eb | 202:7aa061ed387c |
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| 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) | |
| 41 post_delete.connect(on_link_delete, sender=Link) |