Mercurial > public > sg101
changeset 202:7aa061ed387c
Should have added signals.py in r204.
author | Brian Neal <bgneal@gmail.com> |
---|---|
date | Wed, 28 Apr 2010 02:58:07 +0000 (2010-04-28) |
parents | bc958bc3c6eb |
children | 40e5903903e1 |
files | gpp/weblinks/signals.py |
diffstat | 1 files changed, 41 insertions(+), 0 deletions(-) [+] |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/gpp/weblinks/signals.py Wed Apr 28 02:58:07 2010 +0000 @@ -0,0 +1,41 @@ +"""Signals for the weblinks application. +We use signals to compute the denormalized category counts whenever a weblink +is saved.""" +from django.db.models.signals import post_save +from django.db.models.signals import post_delete + +from weblinks.models import Category, Link + + +def on_link_save(sender, **kwargs): + """This function updates the count field for all categories. + It is called whenever a link is saved via a signal. + """ + if kwargs['created']: + # we only have to update the parent category + link = kwargs['instance'] + cat = link.category + cat.count = Link.public_objects.filter(category=cat).count() + cat.save() + else: + # update all categories just to be safe (an existing link could + # have been moved from one category to another + cats = Category.objects.all() + for cat in cats: + cat.count = Link.public_objects.filter(category=cat).count() + cat.save() + + +def on_link_delete(sender, **kwargs): + """This function updates the count field for the link's parent + category. It is called when a link is deleted via a signal. + """ + # update the parent category + link = kwargs['instance'] + cat = link.category + cat.count = Link.public_objects.filter(category=cat).count() + cat.save() + + +post_save.connect(on_link_save, sender=Link) +post_delete.connect(on_link_delete, sender=Link)