#34699: Filtering on annotated TruncSecond expression gives unexpected result.
-------------------------------------+-------------------------------------
Reporter: Stefan | Owner: Francesco
Type: | Panico
Cleanup/optimization | Status: assigned
Component: Database layer | Version: 4.2
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Natalia Bidart):
* type: Uncategorized => Cleanup/optimization
* stage: Unreviewed => Accepted
Comment:
I did some more research on this. I'm accepting this ticket because I do
believe there is an unexpected behavior, which may be a bug or just a
documentation issue.
The simplest test of getting all books and printing their `published` date
and their truncated-to-seconds published date is, IMHO, unexpected: the
`published` value is in UTC but the annotated value is in the timezone the
app is configured. My settings:
{{{
USE_TZ = True
TIME_ZONE = "Europe/Berlin"
}}}
The model:
{{{
from django.db import models
from django.utils import timezone
class Book(models.Model):
published = models.DateTimeField(default=timezone.now)
}}}
In the shell:
{{{
import time
from django.db.models.functions import TruncSecond
from testapp.models import Book
for i in range(3):
Book.objects.create(); time.sleep(1)
annotated_books =
Book.objects.annotate(_published_trunc=TruncSecond('published'))
for i in annotated_books.all():
print(i.published, i._published_trunc)
}}}
With output:
{{{
2023-07-14 18:39:22.620603+00:00 2023-07-14 20:39:22+02:00
2023-07-14 18:39:28.585856+00:00 2023-07-14 20:39:28+02:00
2023-07-14 18:39:29.590469+00:00 2023-07-14 20:39:29+02:00
2023-07-14 18:39:30.595811+00:00 2023-07-14 20:39:30+02:00
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/34699#comment:6>
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