Retrieve objects about to be deleted in cascade in django

Question

Considering those classes:

class Foo(models.Model):
    pass

class Bar(models.Model):
    foo = models.ForeignKey(Foo)

class Baz(models.Model):
    bar = models.ForeignKey(Bar)

class XXX(models.Model):
    field = models.ForeignKey(field_related_to_FOO_somehow)
...

Given an instance foo=Foo.objects.get(...) that a user want to delete, i want to provide him a view of all the objects he's about to delete. Thus, how can i retrieve all the instances of Bar, Baz and all other related objects XXX that will be deleted in cascade if the user confirm?

Could you use the same function as the django admin uses? https://github.com/django/django/blob/1.9.7/django/contrib/admin/utils.py#L119 — Håken Lid, Jun 15 '16 at 08:07
Here's a similar question : http://stackoverflow.com/questions/12158714/how-to-show-related-items-using-deleteview-in-django — user2021091, Jun 15 '16 at 08:11

dmitryro · Answer 1 · 2016-06-15T08:07:05.833

0

foo = Foo.objects.get(id=foo_id)

bar = Bar.objects.filter(foo=foo)

baz = Baz.objects.filter(bar=bar)

baz.delete()
bar.delete()

or just

foo.delete()

edited Jun 15 '16 at 08:07

answered Jun 15 '16 at 07:55

dmitryro

3,463
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I don't want to delete things but know what will be deleted. I don't want to declare explicitely the related objects but want to be generic and retrieve all the related objects recursively – Guillaume Thomas Jun 15 '16 at 08:04
you just delete foo - at the moment you run foo.delete() all the children will be gone – dmitryro Jun 15 '16 at 08:06
That still doesn't work since i'm considering the moment before the deletion. – Guillaume Thomas Jun 18 '16 at 12:28

score 0 · Answer 2 · answered Jun 15 '16 at 08:16

0

You can use on_delete=models.SET_NULL this will set None when delete related objects.

docs.djangoproject.com/en/1.9/ref/models/fields/#foreignkey

answered Jun 15 '16 at 08:16

Rahul Vivek

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Retrieve objects about to be deleted in cascade in django

2 Answers2