#30460: ManyToMany relationships with a custom `through` do not respect
Meta.ordering on the intermediary model
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
ryanpetrello |
Type: Bug | Status: new
Component: Database | Version: 2.2
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
`ManyToManyField`s that specify an intermediary model with a custom
`Meta.ordering` do not inherit that ordering.
{{{#!python
class Dog(models.Model):
pass
class OrderedMembership(models.Model):
class Meta:
ordering = ('position',)
dog = models.ForeignKey('Dog', models.CASCADE)
winner = models.ForeignKey('Winner', models.CASCADE)
position = models.PositiveIntegerField()
class Winner(models.Model):
name = models.CharField(max_length=128)
# OrderedMembership object defined as a class
members = models.ManyToManyField(Dog, through=OrderedMembership)
lassie = Dog('Lassie')
fido = Dog('Fido')
rover = Dog('Rover')
dog_show = Winner(name='Dog Show')
OrderedMembership.objects.create(dog=lassie, winner=dog_show, position=3)
OrderedMembership.objects.create(dog=fido, winner=dog_show, position=2)
OrderedMembership.objects.create(dog=rover, winner=dog_show, position=1)
dog_show.members.all() # <--- does not respect
`OrderedMembership.position`
}}}
This means that if you want to create a custom M2M model that manages
default order via some column on the M2M table:
https://github.com/ansible/awx/pull/3842/files#diff-
ea6da88b8c0cd3fbf7858ae87933b296R995
https://github.com/gregmuellegger/django-
sortedm2m/blob/b48481ebd1212f1af22a6a04d1c8372b5a837350/sortedm2m/fields.py#L41
...it doesn't work as you'd expect (the M2M relation falls back to natural
database order - usually the primary key of the target model).
--
Ticket URL: <https://code.djangoproject.com/ticket/30460>
Django <https://code.djangoproject.com/>
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