[Django] #29330: Regression in master: cannot pickle queryset with expression

[Django]

#29330: Regression in master: cannot pickle queryset with expression
-------------------------------------+-------------------------------------
Reporter: Daniel | Owner: nobody
Miller |
Type: Bug | Status: new
Component: Database | Version: master
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 |
-------------------------------------+-------------------------------------
Removal of `BaseExpression.__getstate__` in
[https://github.com/django/django/pull/9134#pullrequestreview-112057277 PR
9134] caused querysets with expressions derived from `BaseExpression` to
no longer be pickle-able.

Error:

{{{
Traceback (most recent call last):
File "/home/travis/build/millerdev/django-cte/tests/test_recursive.py",
line 212, in test_pickle_recursive_cte_queryset
pickled_qs = pickle.loads(pickle.dumps(regions))
AttributeError: Can't pickle local object
'BaseExpression.convert_value.<locals>.<lambda>'
}}}

Seen here: https://travis-ci.org/millerdev/django-cte/jobs/366128465

Steps to reproduce:

- Clone [https://github.com/dimagi/django-cte django-cte]
- Make a virtualenv any way you prefer.
- `pip install git+https://github.com/django/django.git@master` (or
however you prefer to install django master).
- `pip install nose `
- `nosetests
tests.test_recursive:TestRecursiveCTE.test_pickle_recursive_cte_queryset`
- Observe pickle error.

--
Ticket URL: <https://code.djangoproject.com/ticket/29330>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

[Django]

#29330: Regression in master: cannot pickle queryset with expression
-------------------------------------+-------------------------------------

Reporter: Daniel Miller | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Daniel Miller):

https://github.com/django/django/pull/9878

--
Ticket URL: <https://code.djangoproject.com/ticket/29330#comment:1>

[Django]

#29330: Regression in master: cannot pickle queryset with expression
-------------------------------------+-------------------------------------

Reporter: Daniel Miller | Owner: nobody
Type: Bug | Status: new

Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:

Keywords: | Triage Stage: Ready for
| checkin
Has patch: 0 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Tim Graham):

* stage: Unreviewed => Ready for checkin

--
Ticket URL: <https://code.djangoproject.com/ticket/29330#comment:2>

[Django]

#29330: Regression in master: cannot pickle queryset with expression
-------------------------------------+-------------------------------------

Reporter: Daniel Miller | Owner: nobody

Type: Bug | Status: closed

Component: Database layer | Version: master
(models, ORM) |

Severity: Normal | Resolution: fixed

Keywords: | Triage Stage: Ready for
| checkin

Has patch: 0 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Tim Graham <timograham@…>):

* status: new => closed
* resolution: => fixed

Comment:

In [changeset:"60156750f66fe9e8b95067654b292f12a055393c" 60156750]:
{{{
#!CommitTicketReference repository=""
revision="60156750f66fe9e8b95067654b292f12a055393c"
Fixed #29330 -- Fixed crash when pickling BaseExpression.

Regression in cfff2af02be40106d4759cc6f8bfa476ce82421c.
}}}

--
Ticket URL: <https://code.djangoproject.com/ticket/29330#comment:3>