Support a related_default on OneToOne fields
|Reported by:||rvdrijst||Owned by:||nobody|
|Component:||Database layer (models, ORM)||Version:||master|
|Severity:||Normal||Keywords:||onetoone related expection null|
|Cc:||rvdrijst, eallik@…, olau@…, django@…, Sebastian Goll, Aymeric Augustin, cvrebert, Francis Devereux, mike@…||Triage Stage:||Accepted|
|Has patch:||no||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
Description (last modified by )
EDIT: scroll to comment 13 to see what this ticket is about.
null=True (i.e. it's optional) when there is no value set will return
None, as expected.
However, referencing the reverse side of the relation does not follow this behavior and raises a
For example, in the following situation where
Shops have optionally a
Place (e.g. webshops need not have a physical location):
class Place(models.Model) address = models.CharField(max_length=80) class Shop(models.Model) place = models.OneToOneField(Place, null=True) name = models.CharField(max_length=50) website = models.URLField()
This does work as expected:
>>> s1 = Shop.objects.create(name='Shop', website='shop.com') >>> print s1.place None
But this doesn't work as expected:
>>> p1 = Place.objects.create(address='123 somestr') >>> p1.shop ... [exception stack trace] ... DoesNotExist: Shop matching query does not exist.
I would expect this to be
null is allowed on the
Please correct my if I'm wrong.
I have attached a patch to fix this (checking if
null is allowed and returning
None or raising the exception appropriately), including tests.
Unfortunately this is slightly backwards incompatible, since someone may currently rely on the exception being thrown.
Change History (30)
comment:13 Changed 6 years ago by
|Triage Stage:||Design decision needed → Accepted|
|Type:||Bug → New feature|
comment:23 Changed 5 years ago by
|Summary:||OneToOne fields with null=True raise DoesNotExist exception on related model → Support a related_default on OneToOne fields|