python - How do I override delete() on a model and have it still work with related deletes

Question

I'm having a problem because I'm deleting a Widget by using some_widget_instance.delete(). I also have a model called WidgetFile with an override delete() method so that I can delete files off my hard drive when a WidgetFile is deleted. The problem I'm having is that if I delete a Widget, and it has WidgetFiles related to it like this:

class WidgetFile(models.Model):

    widget = models.ForeignKey(Widget)

Well, when I delete that Widget, it's WidgetFiles are deleted but the delete() method doesn't trigger and do my extra hard drive stuff. Any help is much appreciated.

Answer 1

I'm doing the same thing and noticed a nugget in the Django docs that you should think about.

Overriding predefined model methods

Overriding Delete Note that the delete() method for an object is not necessarily called when deleting objects in bulk using a QuerySet. To ensure customized delete logic gets executed, you can use pre_delete and/or post_delete signals.

This means your snippet will not always do what you want. Using Signals is a better option for dealing with deletions.

I went with the following:

import shutil
from django.db.models.signals import pre_delete 
from django.dispatch import receiver

@receiver(pre_delete)
def delete_repo(sender, instance, **kwargs):
    if sender == Set:
        shutil.rmtree(instance.repo)