Opened 16 years ago
Closed 16 years ago
#10262 closed (duplicate)
Allow to clear object before deleting to avoid data loss because delete cascade behaviour
Reported by: | Manuel Saelices | Owned by: | nobody |
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Component: | Database layer (models, ORM) | Version: | 1.0 |
Severity: | Keywords: | ||
Cc: | Carl Meyer | Triage Stage: | Design decision needed |
Has patch: | yes | Needs documentation: | yes |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description
Imaging a model like this:
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:
>>> 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:
>>> 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:
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.
Attachments (3)
Change History (8)
by , 16 years ago
Attachment: | delete_cascade_option_r9832.diff added |
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by , 16 years ago
Attachment: | delete_cascade_option_with_admin_r9834.diff added |
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by , 16 years ago
Attachment: | delete_cascade_option_with_tests_r9834.diff added |
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With unit tests and with delete_cascade for OneToOneRel
comment:1 by , 16 years ago
Triage Stage: | Unreviewed → Design decision needed |
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comment:2 by , 16 years ago
Needs documentation: | set |
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comment:3 by , 16 years ago
Cc: | added |
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Updated admin to not display objects not deleted (because delete_cascade was False)