#26430: Coalesce in Aggregations ignored when EmptyResultSet returned
-------------------------------------+-------------------------------------
Reporter: Ryan Prater | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.9
(models, ORM) |
Severity: Normal | Resolution:
Keywords: aggregation | Triage Stage: Accepted
coalesce in queryset |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Nick Pope):
Replying to [comment:7 Simon Charette]:
> This happens to be addressed by
https://github.com/django/django/pull/12602
I was looking into reviving https://github.com/django/django/pull/12602.
It seems that some parts of that were already addressed in
c2d4926702045e342a668057f0a758eec9db9436.
Notably this
[https://github.com/django/django/commit/c2d4926702045e342a668057f0a758eec9db9436
#diff-68490047146b30a432d0d7b7793005e89c112289dcb273fa082b4e9df9b81af7R977
solved] the `None` instead of `0` issue for `Count()` in
`aggregation_regress.tests.AggregationTests.test_empty_filter_aggregate`.
It doesn't seem to be true that this ticket will be addressed by that PR
as implied by
[https://github.com/django/django/pull/11715#issuecomment-602050401 this
comment].
Changing the test to use `Coalesce()` as below still fails with
`total_age` being `None`. There is nothing to determine that the second
argument of `Coalesce()` should be used.
{{{#!diff
self.assertEqual(
-
Author.objects.filter(id__in=[]).annotate(Count('friends')).aggregate(Count('pk')),
- {'pk__count': 0},
+
Author.objects.filter(pk__in=[]).annotate(Count('friends')).aggregate(total_age=Coalesce(Sum('age'),
0)),
+ {'total_age': 0},
)
}}}
In the case of `Count()` we get 0 because of `Count.convert_value()`
explicitly returning `0` if the value is `None`.
It seems that https://github.com/django/django/pull/6361 would be the way
forward.
Was there a reason you abandoned that approach, Simon? Would you be happy
for me to pick that up again?
--
Ticket URL: <https://code.djangoproject.com/ticket/26430#comment:8>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/068.84ce98e6dca56f0ac91b6658d3ae12d3%40djangoproject.com.
