#24420: Can't order_by annotated field if annotated field uses conditional
expression
-------------------------------------+-------------------------------------
Reporter: krisfields | Owner: jarshwah
Type: Bug | Status: assigned
Component: Uncategorized | Version: 1.8beta1
Severity: Normal | Resolution:
Keywords: order_by, | Triage Stage: Accepted
annotation, conditional |
expression |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by jarshwah):
See: https://github.com/django/django/pull/4239
Funnily enough, being explicit worked before this patch:
CaseTestModel.objects.filter(integer__lte=2).annotate(test=Case(
When(integer=1, then=2),
When(integer=2, then=1),
default=3,
output_field=models.IntegerField(),
)).order_by(F('test').asc())
The problem is that the same instance of each `When` clause has
resolve_expression called on it multiple times. Once for the annotation,
and once again for the order_by. The problem is that
When.resolve_expression converts the Q() into a WhereNode(), and
overwrites the condition property. It's not idempotent.
--
Ticket URL: <https://code.djangoproject.com/ticket/24420#comment:2>
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