id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
10262	Allow to clear object before deleting to avoid data loss because delete cascade behaviour	Manuel Saelices	nobody	"Imaging a model like this:
{{{
#!python
class Master(models.Model):
    name = models.CharField(max_length=100)
	

class Slave(models.Model):
    name = models.CharField(max_length=100)
    master = models.ForeignKey(Master, null=True)
}}}

And this object creation:
{{{
#!python
>>> m1 = Master.objects.create(name=""master1"")
>>> s1 = Slave.objects.create(name=""slave1"", master=m1)

>>> m1.delete() # this will also delete s1
}}}

Django by default, delete in cascade all related objects... even with {{{null=True}}}.

If you want to avoid this, you can do this:
{{{
#!python
>>> m1.slave_set.clear()
>>> m1.delete()
}}}

This is ok, but it was wonderful if I can change behaviour to not delete cascade. You can think in admin site for example. If you want to delete a Category object you have previously to enter in maybe a hundred objects to set null by hand.

I propose a definition like this:
{{{
#!python
class Slave(models.Model):
    name = models.CharField(max_length=100)
    master = models.ForeignKey(Master, null=True, delete_cascade=False)
}}}

With {{{delete_cascade=False}}} (by default would be {{{True}}}), {{{delete()}}} method will clear this relation previously deletion.

I've attached a patch that implements this idea."		closed	Database layer (models, ORM)	1.0		duplicate		Carl Meyer	Design decision needed	1	1	0	0	0	0