#30246: Using an annotated field calculated with
django.db.models.functions.Extract
in aggregate results in ProgrammingError
-------------------------------------+-------------------------------------
Reporter: Jan Baryła | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 2.1
(models, ORM) |
Severity: Normal | Resolution:
Keywords: query, aggregate, | Triage Stage:
extract, annotate | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Simon Charette):
Hello Jan, thank you for your report.
Just a few questions.
You said the code worked fine on 1.8 but the `Aggregate(filter)` argument
[https://docs.djangoproject.com/en/2.1/topics/db/aggregation/#filtering-
on-annotations was only introduced in Django 2.0] and the `Extact`
function [https://docs.djangoproject.com/en/1.10/ref/models/database-
functions/ was only added in Django 1.10]. Were you using an explicit
`Case(When(...))` in Django 1.8? Does using a `Case(When(...))` on Django
2.1 happens to work around the issue? If not could you try to
[https://docs.djangoproject.com/en/2.1/internals/contributing/triaging-
tickets/#bisecting-a-regression bisect the change that broke it].
You said you tried against 2.1 but did you try against the
[https://pypi.org/project/Django/2.2b1/ current 2.2 beta as well]?
Finally I think your misunderstood how to force the ORM to perform group
by. I think what you are after is something along the lines of
{{{#!python
MyModel.objects.values('usage_time__hour').annotate(Sum('usage'))
}}}
And perform the hour labeling on the python side.
--
Ticket URL: <https://code.djangoproject.com/ticket/30246#comment:1>
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