Hi Jann,
I think you'll need to write a custom deletion handler for this.
The following should work:
from django.db import models
class SetNull(object):
"""Deletion handler that behaves like `SET_NULL` but also
takes a list of extra fields to NULLify."""
def __init__(self, *fields):
self.fields = fields
def __call__(self, collector, field, sub_objs, using):
# Set the field this is attached to NULL
models.SET_NULL(collector, field, sub_objs, using)
for field in self.fields:
models.SET_NULL(collector, field, sub_objs, using)
class MyModel(models.Model):
a = models.CharField(max_length=255, null=True, blank=True)
b = models.ForeignKey(
'MyOtherModel', null=True, blank=True, on_delete=SetNull(a)
)
Simon
Le mardi 25 novembre 2014 12:19:48 UTC-5, Yan a écrit :
>
> Dear Django Users,
>
> I have been running into a problem with the app I am developing and I
> haven't been able to find a good solution. Suppose I have the following
> model:
>
> class MyModel(models.Model):
> a = models.CharField(max_length=255, null=True, blank=True)
> b = models.ForeignKey('MyOtherModel', null=True, blank=True,
> on_delete=models.SET_NULL)
> # some more model fields
>
> The task I am trying to accomplish is the following: If an instance of
> "MyOtherModel" is deleted, a and b of the related MyModel-instance
> should be set to NULL in the database, but the instance of MyModel with
> the other fields should remain. The model above only sets b to NULL but
> not a.
>
> Any ideas?
>
> Regards,
>
> Jann
>
>
--
You received this message because you are subscribed to the Google Groups
"Django users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to django-users+unsubscr...@googlegroups.com.
To post to this group, send email to django-users@googlegroups.com.
Visit this group at http://groups.google.com/group/django-users.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-users/7eefc8b9-07c0-44ad-b402-65715506e64d%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
