[Django] #28724: QuerySet filter across m2m returns incorrect number of objects

[Django]

#28724: QuerySet filter across m2m returns incorrect number of objects
-----------------------------------------+------------------------
               Reporter:  Zach           |          Owner:  nobody
                   Type:  Bug            |         Status:  new
              Component:  Uncategorized  |        Version:  1.11
               Severity:  Normal         |       Keywords:
           Triage Stage:  Unreviewed     |      Has patch:  0
    Needs documentation:  0              |    Needs tests:  0
Patch needs improvement:  0              |  Easy pickings:  0
                  UI/UX:  0              |
-----------------------------------------+------------------------
 {{{#!python
 # models
 from django.db import models

 class ProductArea(models.Model):
   name = models.CharField(max_length=100)

 class Product(models.Model):
   name = models.CharField(max_length=100)
   product_areas = models.ManyToManyField(ProductArea,
 through='Relationship')

 class MembershipLevel(models.Model):
   name = models.CharField(max_length=100)

 class Relationship(models.Model):
   product = models.ForeignKey(Product)
   product_area = models.ForeignKey(ProductArea)
   membership_level = models.ForeignKey(MembershipLevel)
 }}}

 {{{#!python
 from myapp.models import MembershipLevel
 from myapp.models import ProductArea
 from myapp.models import Relationship
 from myapp.models import Product

 p1, _ = Product.objects.get_or_create(name='My Product')
 p2, _ = Product.objects.get_or_create(name='Another Product')
 p3, _ = Product.objects.get_or_create(name='Yet another product')

 a1, _ = ProductArea.objects.get_or_create(name='Air')
 a2, _ = ProductArea.objects.get_or_create(name='Land')
 a3, _ = ProductArea.objects.get_or_create(name='Sea')

 m1, _ = MembershipLevel.objects.get_or_create(name='gold')
 m2, _ = MembershipLevel.objects.get_or_create(name='bronze')
 m3, _ = MembershipLevel.objects.get_or_create(name='silver')

 Relationship.objects.get_or_create(product=p1, product_area=a1,
 membership_level=m1)
 Relationship.objects.get_or_create(product=p1, product_area=a2,
 membership_level=m2)
 Relationship.objects.get_or_create(product=p1, product_area=a3,
 membership_level=m3)
 Relationship.objects.get_or_create(product=p2, product_area=a1,
 membership_level=m1)
 Relationship.objects.get_or_create(product=p2, product_area=a2,
 membership_level=m2)
 Relationship.objects.get_or_create(product=p2, product_area=a3,
 membership_level=m3)
 Relationship.objects.get_or_create(product=p3, product_area=a1,
 membership_level=m1)
 Relationship.objects.get_or_create(product=p3, product_area=a2,
 membership_level=m2)
 Relationship.objects.get_or_create(product=p3, product_area=a3,
 membership_level=m3)

 # "total found: 3".
 print('total found: %s' % Product.objects.count())

 # "total with filter found: 9".
 print('total with filter found: %s' %
 
Product.objects.filter(product_areas__relationship__membership_level__name='gold').count())
 }}}

-- 
Ticket URL: <https://code.djangoproject.com/ticket/28724>
Django <https://code.djangoproject.com/>
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