Mercurial > public > sg101
annotate gpp/downloads/signals.py @ 552:9e42e6618168
For bitbucket issue #2, tweak the admin settings for the Post model to
reduce slow queries. Define our own queryset() method so we can control the
select_related(), and not have it cascade from post to topics to forums to
categories. Removed 'topic' from list_display because MySQL still sucked with
2 inner joins. Now it seems to be tolerable with only one join to User.
| author | Brian Neal <bgneal@gmail.com> |
|---|---|
| date | Wed, 25 Jan 2012 20:07:03 -0600 |
| parents | 3a4bbf9c2cce |
| children |
| rev | line source |
|---|---|
| bgneal@203 | 1 """Signals for the downloads application. |
| bgneal@203 | 2 We use signals to compute the denormalized category counts whenever a download |
| bgneal@203 | 3 is saved.""" |
| bgneal@203 | 4 from django.db.models.signals import post_save |
| bgneal@203 | 5 from django.db.models.signals import post_delete |
| bgneal@203 | 6 |
| bgneal@203 | 7 from downloads.models import Category, Download |
| bgneal@203 | 8 |
| bgneal@203 | 9 |
| bgneal@203 | 10 def on_download_save(sender, **kwargs): |
| bgneal@203 | 11 """This function updates the count field for all categories. |
| bgneal@203 | 12 It is called whenever a download is saved via a signal. |
| bgneal@203 | 13 """ |
| bgneal@203 | 14 if kwargs['created']: |
| bgneal@203 | 15 # we only have to update the parent category |
| bgneal@203 | 16 download = kwargs['instance'] |
| bgneal@203 | 17 cat = download.category |
| bgneal@203 | 18 cat.count = Download.public_objects.filter(category=cat).count() |
| bgneal@203 | 19 cat.save() |
| bgneal@203 | 20 else: |
| bgneal@203 | 21 # update all categories just to be safe (an existing download could |
| bgneal@203 | 22 # have been moved from one category to another |
| bgneal@203 | 23 cats = Category.objects.all() |
| bgneal@203 | 24 for cat in cats: |
| bgneal@203 | 25 cat.count = Download.public_objects.filter(category=cat).count() |
| bgneal@203 | 26 cat.save() |
| bgneal@203 | 27 |
| bgneal@203 | 28 |
| bgneal@203 | 29 def on_download_delete(sender, **kwargs): |
| bgneal@203 | 30 """This function updates the count field for the download's parent |
| bgneal@203 | 31 category. It is called when a download is deleted via a signal. |
| bgneal@203 | 32 """ |
| bgneal@203 | 33 # update the parent category |
| bgneal@203 | 34 download = kwargs['instance'] |
| bgneal@203 | 35 cat = download.category |
| bgneal@203 | 36 cat.count = Download.public_objects.filter(category=cat).count() |
| bgneal@203 | 37 cat.save() |
| bgneal@203 | 38 |
| bgneal@203 | 39 |
| bgneal@260 | 40 post_save.connect(on_download_save, sender=Download, |
| bgneal@260 | 41 dispatch_uid='downloads.signals') |
| bgneal@260 | 42 post_delete.connect(on_download_delete, sender=Download, |
| bgneal@260 | 43 dispatch_uid='downloads.signals') |