Commit f4132140 authored by Anssi Kääriäinen's avatar Anssi Kääriäinen
Browse files

[1.5.x] Fixed #19652 -- Fixed .none() regression in related fields 

The regression was caused by using .none() when querying for related
models, and the origin field's value was None. This resulted in missing
custom related manager subclass as .none() returns plain QuerySet.

This isn't backport from master, in master .none() correctly preserves
the queryset's class.

Patch provided by Simon Charette, with some minor polish by committer.
parent 54887d68

django/db/models/fields/related.py

+2 −1
Original line number Diff line number Diff line
@@ -498,7 +498,8 @@ class ForeignRelatedObjectsDescriptor(object): 
                    db = self._db or router.db_for_read(self.model, instance=self.instance)

                    qs = super(RelatedManager, self).get_query_set().using(db).filter(**self.core_filters)

                    if getattr(self.instance, attname) is None:

                        return qs.none()

                        # We don't want to use qs.none() here, see #19652

                        return qs.filter(pk__in=[])

                    qs._known_related_objects = {rel_field: {self.instance.pk: self.instance}}

                    return qs

tests/modeltests/custom_managers/models.py

+21 −0
Original line number Diff line number Diff line
@@ -63,3 +63,24 @@ class Car(models.Model): 


    def __str__(self):

        return self.name





# Bug #19652

class ObjectQuerySet(models.query.QuerySet):

    pass



class ObjectManager(models.Manager):

    use_for_related_fields = True



    def get_query_set(self):

        return ObjectQuerySet(self.model, using=self._db)





class RelatedObject(models.Model):

    pass





class Object(models.Model):

    related = models.ForeignKey(RelatedObject, related_name='objs')



    objects = ObjectManager()

tests/modeltests/custom_managers/tests.py

+12 −1
Original line number Diff line number Diff line
@@ -3,7 +3,8 @@ from __future__ import absolute_import 
from django.test import TestCase

from django.utils import six



from .models import Person, Book, Car, PersonManager, PublishedBookManager

from .models import (ObjectQuerySet, RelatedObject, Person, Book, Car, PersonManager,

    PublishedBookManager)





class CustomManagerTests(TestCase):
@@ -72,3 +73,13 @@ class CustomManagerTests(TestCase): 
            ],

            lambda c: c.name

        )



    def test_related_manager(self):

        """

        Make sure un-saved object's related managers always return an instance

        of the same class the manager's `get_query_set` returns. Refs #19652.

        """

        rel_qs = RelatedObject().objs.all()

        self.assertIsInstance(rel_qs, ObjectQuerySet)

        with self.assertNumQueries(0):

            self.assertFalse(rel_qs.exists())