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bgneal@922
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1 """Signal handlers for the downloads application.
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bgneal@922
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2
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bgneal@203
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3 We use signals to compute the denormalized category counts whenever a download
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bgneal@922
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4 is saved.
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bgneal@922
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5
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bgneal@922
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6 """
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bgneal@203
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7 from django.db.models.signals import post_save
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bgneal@203
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8 from django.db.models.signals import post_delete
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bgneal@203
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9
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bgneal@664
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10 from downloads.models import Category, Download, PendingDownload
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bgneal@203
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11
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bgneal@203
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12
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bgneal@203
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13 def on_download_save(sender, **kwargs):
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bgneal@203
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14 """This function updates the count field for all categories.
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bgneal@203
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15 It is called whenever a download is saved via a signal.
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bgneal@203
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16 """
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bgneal@203
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17 if kwargs['created']:
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bgneal@203
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18 # we only have to update the parent category
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bgneal@203
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19 download = kwargs['instance']
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bgneal@203
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20 cat = download.category
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bgneal@203
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21 cat.count = Download.public_objects.filter(category=cat).count()
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bgneal@203
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22 cat.save()
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bgneal@203
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23 else:
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bgneal@203
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24 # update all categories just to be safe (an existing download could
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bgneal@203
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25 # have been moved from one category to another
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bgneal@203
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26 cats = Category.objects.all()
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bgneal@203
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27 for cat in cats:
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bgneal@203
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28 cat.count = Download.public_objects.filter(category=cat).count()
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bgneal@203
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29 cat.save()
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bgneal@203
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30
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bgneal@203
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31
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bgneal@203
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32 def on_download_delete(sender, **kwargs):
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bgneal@203
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33 """This function updates the count field for the download's parent
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bgneal@203
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34 category. It is called when a download is deleted via a signal.
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bgneal@664
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35
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bgneal@664
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36 We now delete the uploaded file when the download is deleted.
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bgneal@203
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37 """
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bgneal@203
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38 # update the parent category
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bgneal@203
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39 download = kwargs['instance']
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bgneal@203
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40 cat = download.category
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bgneal@203
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41 cat.count = Download.public_objects.filter(category=cat).count()
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bgneal@203
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42 cat.save()
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bgneal@203
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43
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bgneal@664
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44 # delete the actual file
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bgneal@664
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45 if download.file:
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bgneal@664
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46 download.file.delete(save=False)
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bgneal@664
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47
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bgneal@664
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48
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bgneal@664
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49 def on_pending_download_delete(sender, **kwargs):
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bgneal@664
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50 """Delete the uploaded file if it exists."""
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bgneal@664
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51
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bgneal@664
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52 download = kwargs['instance']
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bgneal@664
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53 # delete the actual file
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bgneal@664
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54 if download.file:
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bgneal@664
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55 download.file.delete(save=False)
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bgneal@664
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56
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bgneal@203
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57
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bgneal@260
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58 post_save.connect(on_download_save, sender=Download,
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bgneal@922
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59 dispatch_uid='downloads.receivers')
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bgneal@260
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60 post_delete.connect(on_download_delete, sender=Download,
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bgneal@922
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61 dispatch_uid='downloads.receivers')
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bgneal@664
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62 post_delete.connect(on_pending_download_delete, sender=PendingDownload,
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bgneal@922
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63 dispatch_uid='downloads.receivers')
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