Model instance no longer has a _default_manager attribute

[Raffaele Salmaso]

Given a model

from django.db import models

class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

In django < 1.10

In [1]: from polls.models import Question

In [2]: q = Question.objects.last()

In [3]: Question._default_manager
Out[3]: <django.db.models.manager.Manager at 0x7ff799637f28>

In [4]: q._default_manager
Out[4]: <django.db.models.manager.Manager at 0x7ff799637f28>

In django >= 1.10

In [1]: from polls.models import Question

In [2]: q = Question.objects.last()

In [3]: Question._default_manager
Out[3]: <django.db.models.manager.Manager at 0x7f5e0721d4a8>

In [4]: q._default_manager
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-4-2c5c6f28a506> in <module>()
----> 1 q._default_manager

AttributeError: 'Question' object has no attribute '_default_manager'

In [5]: q._meta.default_manager
Out[5]: <django.db.models.manager.Manager at 0x7f5e0721d4a8>

It's an intenden behaviour?
If so, it lacks a notice in releases note and/or manager docs.

I found it testing my project with django-paypal (​https://github.com/spookylukey/django-paypal/blob/79b22278b658b2fc618771ca7c471ea398455147/paypal/standard/helpers.py#L24)

[Tim Graham]

Bisected to ed0ff913c648b16c4471fc9a9441d1ee48cb5420.

[Loic Bistuer]

Managers were never intended to be accessible on model instances, we even ​use a descriptor to prevent that usage but _default_manager somehow escaped that restriction. I guess we can mention the change in the release notes.

For completeness I'll mention that if we really wanted these available on the instance we could just redeclare the properties from ModelBase on models.Model, but I don't think we should.

[Tim Graham]

​PR

[Raffaele Salmaso]

Ok, thanks.
I'll open a ticket on django-paypal.

[Tim Graham <timograham@…>]

In 0e7e47b5:

Fixed #26652 -- Documented removal of model instance _(default/base)_manager attributes.

[Tim Graham <timograham@…>]

In 9985544:

[1.10.x] Fixed #26652 -- Documented removal of model instance _(default/base)_manager attributes.

Backport of 0e7e47b5d7123441efc03545da59a6cd581c04b1 from master