How to "create or update" using F object?

user_4471283 0
Viewed 614

I need to create LeaderboardEntry if it is not exists. It should be updated with the new value (current + new) if exists. I want to achieve this with a single query. How can I do that?

Current code looking like this: (2 queries)

reward_amount = 50

LeaderboardEntry.objects.get_or_create(player=player)
LeaderboardEntry.objects.filter(player=player).update(golds=F('golds') + reward_amount)

PS: Default value of "golds" is 0.

django-queryset django-models django
3 Answers

you can have one query hit less with the defaults :

reward_amount = 50

leader_board, created = LeaderboardEntry.objects.get_or_create(
    player=player,
    defaults={
        "golds": reward_amount,
    }
)

if not created:
    leader_board.golds += reward_amount
    leader_board.save(update_fields=["golds"])
user_50733770

I think your problem is the get_or_create() method so it return back a tuple with two values, (object, created) so you have to recieve them in your code as following:

reward_amount = 50

entry, __ = LeaderboardEntry.objects.get_or_create(player=player)
entry.golds += reward_amount
entry.save()

It will work better than your actual code, just will avoid make two queries.

Of course the save() method will hit again your database.

user_10484040

You can solve this with update_or_create:

LeaderboardEntry.objects.update_or_create(
    player=player,
    defaults={
        'golds': F('golds') + reward_amount
    }
)

EDIT:

Sorry, F expressions in update_or_create are not yet supported.

user_67598440
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