get().delete() does not work, filter().delete() works?

[Rainy]

Hi, I have a function that accepts a pk and deletes an object:

Item.objects.filter(pk=pk).delete()

If I change it to:

Item.objects.get(pk=pk).delete()

it no longer works, without any errors. I tried it using exactly the
same object. I looked at django docs for deletion, the only difference
they mention is that with .filter(), it will also do bulk deletion.

What is the reason for this behaviour? Thanks!

[Tom Evans]

Those are two very different methods, instance.delete() on a model
calls the instance's delete method, which (eventually) via the
Model.delete() method, sends a pre_delete signal, issues a SQL
statement to delete that row from the database and finally issues a
post_delete signal.

queryset.delete() does not do any of that, it simply constructs a
"DELETE FROM ... WHERE ..." query and executes it.

So why does your instance.delete() not work? Top contenders:

1) You have overridden the delete() method, and you don't call the
super class method
2) You have a pre_delete signal that refuses the deletion (altho I
think you would receive an exception in this case?)
3) Something I haven't considered \o/

Cheers

Tom

[Rainy]

On Friday, March 16, 2012 2:50:25 PM UTC-4, Tom Evans wrote:

1) You have overridden the delete() method, and you don't call the

super class method

Indeed, I had overridden it to create a delete column and forgot about it!

Thanks.  Rainy