#25287: Multiplying and dividing connectors for datetime expressions are not
supported by sqlite backed.
-------------------------------------+-------------------------------------
Reporter: Ahmet DAL | Owner: nobody
Type: New feature | Status: new
Component: Database layer | Version: 3.0
(models, ORM) |
Severity: Normal | Resolution:
Keywords: sqlite3, | Triage Stage: Accepted
combine_duration_expression, F |
expressions, |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Baptiste Mispelon):
* version: 1.8 => 3.0
Comment:
I was able to reproduce the reported error on the latest master
(a5855c8f0fe17b7e888bd8137874ef78012a7294) by using the following models:
{{{
#!python
from django.db import models
class Ticket(models.Model):
date_opened = models.DateTimeField()
class Rule(models.Model):
duration = models.DurationField()
class Action(models.Model):
percent = models.FloatField()
rule = models.ForeignKey('Rule', on_delete=models.CASCADE)
class Expire(models.Model):
ticket = models.ForeignKey('Ticket', on_delete=models.CASCADE)
action = models.ForeignKey('Action', on_delete=models.CASCADE)
}}}
And the following testcase:
{{{
#!python
from datetime import timedelta
from django.db.models import F
from django.test import TestCase
from django.utils import timezone
from .models import Ticket, Rule, Action, Expire
class TicketTestCase(TestCase):
def test_ticket(self):
now = timezone.now()
ticket1 = Ticket.objects.create(date_opened=now-timedelta(days=6))
ticket2 = Ticket.objects.create(date_opened=now-timedelta(days=4))
rule = Rule.objects.create(duration=timedelta(days=10))
action = Action.objects.create(rule=rule, percent=50)
expire = Expire.objects.create(ticket=ticket1, action=action)
expire = Expire.objects.create(ticket=ticket2, action=action)
qs =
Expire.objects.filter(ticket__date_opened__lte=(timezone.now() -
F("action__percent") * F("action__rule__duration") / 100))
self.assertQuerysetEqual(qs, [ticket1.pk], transform=lambda x:
x.ticket.pk)
}}}
As described in the original ticket, the testcase fails with sqlite
(`DatabaseError: Invalid connector for timedelta: *.`) but passes when
using postgresql.
The proposed solution of adding the new `*` and `/` operators to
`sqlite3.DatebaseOperations.combine_duration_expression()` [1] only works
in that the `DatebaseError` disappears but the test still fails because
the returned queryset is empty.
Josh's suggestions of wrapping everything in an `ExpressionWrapper` don't
seem to make a difference either.
[1]
https://github.com/django/django/blob/a5855c8f0fe17b7e888bd8137874ef78012a7294/django/db/backends/sqlite3/operations.py#L315
--
Ticket URL: <https://code.djangoproject.com/ticket/25287#comment:7>
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