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
12708	Django raises DoesNotExist when consulting an empty ForeignKey field	Luc Saffre	nobody	"{{{
""""""

Django raises DoesNotExist when consulting an empty ForeignKey field

We create an Order without a Journal::
  
  >>> o = Order()
  >>> print o.journal
  None
  >>> o.save()
 
This works only because `Order.journal` has `null=True`.
In fact I want the `save()` method to complain if `journal` is empty,
so I remove `null=True` from the field definition.

  >>> o = Order2()
  >>> print o.journal
  None
  
The above line raises a DoesNotExist exception. Django should raise 
an exception only when I try to save the instance, not already when 
I want to see the value of `journal`!

""""""

from django.db import models
   
class Journal(models.Model):
    pass

class Order(models.Model):
    journal = models.ForeignKey(Journal,null=True)

class Order2(models.Model):
    journal = models.ForeignKey(Journal)

}}}"	Cleanup/optimization	closed	Database layer (models, ORM)	dev	Normal	invalid	ForeignKey DoesNotExist	simon@… k@…	Unreviewed	0	0	0	0	0	0