#24385: Sum() doesn't seem to respect .distinct() in the queryset filter before
.aggregate() when filtering by m2m.
-------------------------------------+-------------------------------------
Reporter: mcagl | Owner: nobody
Type: Uncategorized | Status: new
Component: Database layer | Version: 1.7
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by mcagl):
* needs_better_patch: => 0
* needs_tests: => 0
* version: 1.6 => 1.7
* needs_docs: => 0
Old description:
> Hello,
> I setup a minimal project here:
> https://github.com/mcagl/minimal_django_sum_test to demonstrate the
> problem.
>
> I'm working with Django 1.6.x and I noticed something that I don't
> understand.
>
> As you can see from the github repository, I have a Tag model and a Row
> model with a m2m towards Tag and a DecimalField called amount.
>
> If I filter Row objects for more than one Tag, and there is/are Row
> objects that have more than one Tag among the one filtered by,
> Sum('amount') counts it/them once per Tag, even if I use distinct().
>
> Please note also that I assert, in the test, that the filtered queryset
> is composed by three Row objects, as expected, but the next assert fails,
> with 40 != 30.
>
> I added a test that instead of aggregate(Sum('amount')) does
> sum([x.amount for x in rows]) which passes.
>
> Is this a bug in Sum() or am I missing something?
>
> Kind regards,
> Mark
New description:
Hello,
I setup a minimal project here:
https://github.com/mcagl/minimal_django_sum_test to demonstrate the
problem.
I'm working with Django 1.6.x and I noticed something that I don't
understand.
Edit: I checked also with the last stable version, 1.7.4 downloaded right
from the website, and the problem is still there.
As you can see from the github repository, I have a Tag model and a Row
model with a m2m towards Tag and a DecimalField called amount.
If I filter Row objects for more than one Tag, and there is/are Row
objects that have more than one Tag among the one filtered by,
Sum('amount') counts it/them once per Tag, even if I use distinct().
Please note also that I assert, in the test, that the filtered queryset is
composed by three Row objects, as expected, but the next assert fails,
with 40 != 30.
I added a test that instead of aggregate(Sum('amount')) does sum([x.amount
for x in rows]) which passes.
Is this a bug in Sum() or am I missing something?
Kind regards,
Mark
--
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Ticket URL: <https://code.djangoproject.com/ticket/24385#comment:1>
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