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
1667	OneToOne and ForeignKey related objects are cached differently	Maniac <Maniac@…>	nobody	"Looks like ForeignKeys respect model's custom default manager and OneToOneField don't. Here's an example.

There are 3 models: Author, Article and Contact. Article refers to Author with ForeignKey and Contact refers to Author with OneToOneField. Author has a custom default manager that gives out only authors with their 'available' field set to True:

{{{
class AvailableAuthorManager(models.Manager):
  def get_query_set(self):
    return super(AvailableAuthorManager, self).get_query_set().filter(available__exact=True)

class Author(models.Model):
  name = models.CharField(maxlength=50)
  available = models.BooleanField(default=True)
  
  objects = AvailableAuthorManager()
  
class Article(models.Model):
  author = models.ForeignKey(Author)
  title = models.CharField(maxlength=50)
  
class Contact(models.Model):
  author = models.OneToOneField(Author)
  address = models.CharField(maxlength=50)
}}}

Then if you have an author with available=False and an article and a contact reefering to it you get:

 * article.author -- raises an exception DoesNotExist
 * contact.author -- returns the author

Looks like this should behave the same way in both cases. However I'm not sure how exactly but I tend to think that it should raise an exception because managers are supposed to be the ultimate mechanism to access model objects."	defect	closed	Database layer (models, ORM)	dev	normal	fixed	121-rewrite		Design decision needed	0	0	0	0	0	0