#25861: Performing two conditional counts on foreign key fields
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Reporter: luccascorrea | Owner: nobody
Type: Uncategorized | Status: new
Component: Uncategorized | Version: 1.8
Severity: Normal | Resolution:
Keywords: QuerySet.extra | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by jarshwah):
Does this query work correctly?
{{{
from django.db.models import Count
from django.db.models.expressions import Case, When
likes = Q()
Article.objects.annotate(
likes=Count(
Case(When(articlelike__date__gte=F('pubdate'), then=1, else=0)),
distinct=True
),
views=Count(
Case(When(articleview__date__gte=F('pubdate'), then=1, else=0)),
distinct=True
)
)
}}}
I'm guessing this will result in duplicates also, but can you give it a
try anyway?
The ORM doesn't do aggregation across multiple reverse relations (or m2m
relations) very well. I'm not too certain about the reason unfortunately.
Anssi would know better than I, but I suspect it has something to do with
not creating subqueries.
--
Ticket URL: <https://code.djangoproject.com/ticket/25861#comment:2>
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