Commit 4fea46a0 authored by Luke Plant's avatar Luke Plant
Browse files

Fixed #18309 - Prefetch related does not work for fkey to multitable inherited model 

Thanks to milosu for the report, tests and initial patch.
parent f0664dc8

django/db/models/fields/related.py

+2 −2
Original line number Diff line number Diff line
@@ -329,10 +329,10 @@ class ReverseSingleRelatedObjectDescriptor(object): 
            return QuerySet(self.field.rel.to).using(db)



    def get_prefetch_query_set(self, instances):

        rel_obj_attr = attrgetter(self.field.rel.field_name)

        other_field = self.field.rel.get_related_field()

        rel_obj_attr = attrgetter(other_field.attname)

        instance_attr = attrgetter(self.field.attname)

        instances_dict = dict((instance_attr(inst), inst) for inst in instances)

        other_field = self.field.rel.get_related_field()

        if other_field.rel:

            params = {'%s__pk__in' % self.field.rel.field_name: instances_dict.keys()}

        else:

tests/modeltests/prefetch_related/models.py

+3 −0
Original line number Diff line number Diff line
@@ -68,6 +68,9 @@ class Reader(models.Model): 
    class Meta:

        ordering = ['id']



class BookReview(models.Model):

    book = models.ForeignKey(BookWithYear)

    notes = models.TextField(null=True, blank=True)



## Models for default manager tests

tests/modeltests/prefetch_related/tests.py

+11 −1
Original line number Diff line number Diff line
@@ -7,7 +7,7 @@ from django.test.utils import override_settings 


from .models import (Author, Book, Reader, Qualification, Teacher, Department,

    TaggedItem, Bookmark, AuthorAddress, FavoriteAuthors, AuthorWithAge,

    BookWithYear, Person, House, Room, Employee, Comment)

    BookWithYear, BookReview, Person, House, Room, Employee, Comment)





class PrefetchRelatedTests(TestCase):
@@ -335,6 +335,10 @@ class MultiTableInheritanceTest(TestCase): 
        self.authorAddress = AuthorAddress.objects.create(

            author=self.author1, address='SomeStreet 1')

        self.book2.aged_authors.add(self.author2, self.author3)

        self.br1 = BookReview.objects.create(

            book=self.book1, notes="review book1")

        self.br2 = BookReview.objects.create(

            book=self.book2, notes="review book2")



    def test_foreignkey(self):

        with self.assertNumQueries(2):
@@ -343,6 +347,12 @@ class MultiTableInheritanceTest(TestCase): 
                         for obj in qs]

        self.assertEqual(addresses, [[unicode(self.authorAddress)], [], []])



    def test_foreignkey_to_inherited(self):

        with self.assertNumQueries(2):

            qs = BookReview.objects.prefetch_related('book')

            titles = [obj.book.title for obj in qs]

        self.assertEquals(titles, ["Poems", "More poems"])



    def test_m2m_to_inheriting_model(self):

        qs = AuthorWithAge.objects.prefetch_related('books_with_year')

        with self.assertNumQueries(2):