select_related doesn't work correctly when mixing nullable and non-nullable keys

[Michał Bartoszkiewicz]

The following models:

class Model1(models.Model):
    x = models.ForeignKey('Model2', null=True)

class Model2(models.Model):
    y = models.ForeignKey('Model3', null=False)

class Model3(models.Model):
    z = models.ForeignKey('Model4', null=False)

class Model4(models.Model):
    q = models.IntegerField()

cause a problem with select_related():

In [4]: models.Model1.objects.select_related('x__y')
Out[4]: [<Model1: Model1 object>]

In [5]: models.Model1.objects.select_related('x__y__z')
Out[5]: []

It look like the fix for #7369 only fixed a case when a single non-nullable ForeignKey is encountered, not when there are two in a row.

[Michał Bartoszkiewicz]

The attached patch fixes the problem for me.

[Luke Plant]

(In [12719]) Fixed #12240 - select_related doesn't work correctly when mixing nullable and non-nullable keys

Thanks to embe for report and Alex for fix.

[Luke Plant]

(In [12720]) [1.1.X] Fixed #12240 - select_related doesn't work correctly when mixing nullable and non-nullable keys

Thanks to embe for report and Alex for fix.

Backport of 12719 from trunk.

[Jacob]

Milestone 1.2 deleted