Commit 4fd94969 authored by Luke Plant's avatar Luke Plant
Browse files

Fixed #19607 - prefetch_related crash 

Thanks to av@rdf.ru and flarno11@yahoo.de for the report.
parent 48424ada

django/db/models/query.py

+7 −2
Original line number Diff line number Diff line
@@ -1558,8 +1558,13 @@ def prefetch_related_objects(result_cache, related_lookups): 
                        good_objects = False

                        break

                else:

                    # We already did this list

                    break

                    # Since prefetching can re-use instances, it is possible to

                    # have the same instance multiple times in obj_list. So we

                    # can reach this branch either because we did all of

                    # obj_list already, or because we did 'obj' earlier in this

                    # iteration over obj_list. In the first case we could

                    # shortcut and exit the loop, but not in the second.

                    continue

            if not good_objects:

                break

tests/prefetch_related/models.py

+20 −0
Original line number Diff line number Diff line
@@ -195,3 +195,23 @@ class Employee(models.Model): 


    class Meta:

        ordering = ['id']





### Ticket 19607



@python_2_unicode_compatible

class LessonEntry(models.Model):

    name1 = models.CharField(max_length=200)

    name2 = models.CharField(max_length=200)



    def __str__(self):

        return "%s %s" % (self.name1, self.name2)





@python_2_unicode_compatible

class WordEntry(models.Model):

    lesson_entry = models.ForeignKey(LessonEntry)

    name = models.CharField(max_length=200)



    def __str__(self):

        return "%s (%s)" % (self.name, self.id)

tests/prefetch_related/tests.py

+24 −1
Original line number Diff line number Diff line
@@ -8,7 +8,8 @@ from django.utils import six 


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

    TaggedItem, Bookmark, AuthorAddress, FavoriteAuthors, AuthorWithAge,

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

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

    LessonEntry, WordEntry)





class PrefetchRelatedTests(TestCase):
@@ -618,3 +619,25 @@ class MultiDbTests(TestCase): 
            ages = ", ".join(str(a.authorwithage.age) for a in A.prefetch_related('authorwithage'))



        self.assertEqual(ages, "50, 49")





class Ticket19607Tests(TestCase):



    def setUp(self):



        for id, name1, name2 in [

            (1, 'einfach', 'simple'),

            (2, 'schwierig', 'difficult'),

            ]:

            LessonEntry.objects.create(id=id, name1=name1, name2=name2)



        for id, lesson_entry_id, name in [

            (1, 1, 'einfach'),

            (2, 1, 'simple'),

            (3, 2, 'schwierig'),

            (4, 2, 'difficult'),

            ]:

            WordEntry.objects.create(id=id, lesson_entry_id=lesson_entry_id, name=name)



    def test_bug(self):

        list(WordEntry.objects.prefetch_related('lesson_entry', 'lesson_entry__wordentry_set'))