Can't use order_by and values(_list) together after annotating

[Adrian Wielgosik]

Example:

# model

from django.db import models
class Table(models.Model):
    value = models.IntegerField()

# tests

from django.test import TestCase
from testapp.models import Table
from django.db.models import IntegerField, Case, Value, When
class Test1(TestCase):
    def test_1(self):
        query = Table.objects.annotate(
            other=Case(
                When(value=11, then=Value(1)),
                output_field=IntegerField()
            ),
        ).order_by('other', 'value').values('id')

        print query

The error is:

AttributeError: 'WhereNode' object has no attribute 'resolve_expression'

[Tim Graham]

Attached is a test to reproduce the crash (at 956df84a613d4b9a92c979e46557243d288282c8).

[Josh Smeaton]

This looks related to #25307

[Lucas Moeskops]

I think this is not an issue.

The problem is that the example is annotating a field and then sorts on this field. To do this, the field needs to exist still in the select. It is however thrown away by values, so it can't sort on it.

The example will work correctly if the annotated field is added to the values list as well. It will also work correctly if no order on the annotated field is applied.

If this were to work, the resulting query would be considerably more complex, involving a different final select than the select to apply the ordering on.

What could be improved though is the error message. This is clear when no annotation is used. Maybe something like "Can't deselect annotated value" or "Can't order on unselected annotated field other"?

[Anssi Kääriäinen]

We do add "unselected" fields to the end of select list for some cases already. It is perhaps possible to do so here, too.

[varun naganathan]

I don't think the problem is because the field is not available in the select.
When I use an inbuilt function like "Count" to annotate instead of the "When" and "then" clause,the error doesnt seem to appear.
If the field used to sort not being available in select was the problem,even use of "annotate" with "Count" would give the same error.
Edit:
On top of that even if "When" and "Then" is used with the field not being used in the annotation but not included in the "fields",still no error occurs.
I'm thus persuaded to feel that the "When" and "Then" statements are causing the error.

[varun naganathan]

Please review PR
​https://github.com/django/django/pull/5852
I'm new to contributing to django.Sorry if I wasn't supposed to self assign the bug to me.

[Tim Graham <timograham@…>]

In 3eba9638:

Fixed #25316 -- Fixed a crash with order_by() and values() after annotate().

[Tim Graham <timograham@…>]

In f6b4893:

[1.8.x] Fixed #25316 -- Fixed a crash with order_by() and values() after annotate().

Backport of 3eba9638ee69138c73efb1d1c1d1b806ddafc6cf from master

[Tim Graham <timograham@…>]

In 5770c23:

[1.9.x] Fixed #25316 -- Fixed a crash with order_by() and values() after annotate().

Backport of 3eba9638ee69138c73efb1d1c1d1b806ddafc6cf from master