CODEWITHSUNDEEP
django
jay_kir
jay_kir

Reputation: 23

Django Filter all objects that contain latest date

I'm performing two queries to obtain all of the latest matches as shown below. Is there a more efficient way to retrieve all match objects that have the same latest date?

class Match(models.Model):
    team = models.CharField()
    round_date = models.DateField()

date = Match.objects.latest('round_date').round_date
Match.objects.filter(round_date=date)

Upvotes: 1

Views: 134

Answers (1)

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 476574

You can use a Subquery [Django-doc] here:

from django.db.models import Subquery

maximal = Match.objects.order_by('-round_date').values('round_date')[:1]
Match.objects.filter(round_date=Subquery(maximal))

which will perform a single query:

SELECT match.id, match.round_date
FROM match
WHERE match.round_date = (
    SELECT U0.round_date
    FROM match U0
    ORDER BY U0.round_date DESC
    LIMIT 1
)

The maximal query is thus - unless you would of course "consume" it - not evaluated, but is used to construct a subquery.

In case the field on which you order can be NULLable, this is not the case here, I advise to use an .order_by(F('round_date').desc(nulls_last=True)).

Upvotes: 2

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