Override delete-function on multi-delete

Question

The following works great when going to the objects adminpage and select delete. The problem is that when using multiselect and deleting multiple items at once it doesn't use my delete-override. I've been looking for a solution but haven't found one so it's time to turn to the masters ;)

class Photo(models.Model):
    name = models.CharField(max_length=256, unique=True)
    slug = models.SlugField(unique=True)
    image = models.ImageField(upload_to='photos/')

    def delete(self):
        super(Photo, self).delete()
        ### Check if the dir is empty, then remove the folder
        ph = Photo.objects.filter(album=self.album)
        if ph.count() == 0:
            rmtree(os.path.join(settings.MEDIA_ROOT, 'photos/' + self.album.slug))

In a multiprocessed situation it is possible for one connection to delete the last Photo in an album while another connection is in the middle of uploading a Photo to that album. Not having seen the code that creates the directory it is impossible to have a firm understanding of how racy this code is, but I wouldn't risk running on my server. — Ignacio Vazquez-Abrams, Jan 13 '10 at 22:41
This has been asked before: http://stackoverflow.com/questions/1471909/django-model-delete-not-triggered — Dominic Rodger, Jan 14 '10 at 06:44

score 3 · Accepted Answer · answered Jan 14 '10 at 12:09

Solved my problem :)

class PhotoQuerySet(QuerySet):
    def delete(self):
        for x in self:
            x.delete()

class PhotoManager(models.Manager):
    def get_query_set(self):
        return PhotoQuerySet(self.model)

class Photo(models.Model):
    name = models.CharField(max_length=256, unique=True)
    slug = models.SlugField(unique=True)
    image = models.ImageField(upload_to='photos/')

    objects = PhotoManager()

    def delete(self):
        os.remove(self.get_thumbnail_name())
        os.remove(self.get_medium_name())
        super(Photo, self).delete()

score 1 · Answer 2 · answered Jul 12 '12 at 13:43

Just for completeness, the model's delete method isn't called on a Model.objects.filter(...).delete() call: https://docs.djangoproject.com/en/dev/ref/models/querysets/#django.db.models.query.QuerySet.delete

Django sends two signals, pre_delete and post_delete, after a Model.objects.filter(...).delete() call. More info here: https://docs.djangoproject.com/en/dev/ref/signals/#pre-delete

score 0 · Answer 3 · answered Jan 13 '10 at 23:20

0

when using multiselect and deleting multiple items at once

I suspect this means you're doing something like:

Photo.objects.filter(name='something').delete()

If that's the case, that will not call your custom delete method since it uses the delete method on a queryset. While not very efficient, you can force your delete method to be called by:

for photo in Photo.objects.filter(name='something'):
    photo.delete()

answered Jan 13 '10 at 23:20

brianz

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I'll try and override the queryset delete-method and use that to run my custom delete-function. – xintron Jan 14 '10 at 08:32

Override delete-function on multi-delete

3 Answers3