CODEWITHSUNDEEP
pythondjango
Joey Coder
Joey Coder

Reputation: 3519

Get all objects that have entries in another model

class Event(HashidModel, TimeStampedModel):
    organizer = models.ForeignKey(
        "organizers.Organizer", on_delete=models.CASCADE, related_name="events"
    )

How do I get all organizers, that have existing events? My challenge is that I have to go through the organizer (I can't start from the event mode.l)

organizer = Organizer.objects.all()

Upvotes: 1

Views: 24

Answers (1)

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 477035

You can filter with:

Organizer.objects.filter(
    events__isnull=False
).distinct()

This works since we perform a LEFT OUTER JOIN on the Event table, and then filter such that we only retrieve items for wich the id of the Event is NOT NULL. We then take the DISTINCT objects to avoid retrieving the Organizer multiple times, one per Event.

Normally Django will optimize this to an INNER JOIN.

Upvotes: 2

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