Django sum on query set

Question

I have a queryset in django with condition as follows:

query_set = MyModel.objects.annotate(TWWByRuns=(
    Case(
        When(Q(toss_winner=F('winner')) & Q(win_by_runs=0), then=1),
        output_field=FloatField(), default=0)
    )
).values('TWWByRuns')

I would like to use django built-in sum function to add whenever the value in the query_set equals to 1 as in when then=1. I know to use the sum function without conditionals but here since I have condition where should I use the sum function in this query_set?

willeM_ Van Onsem · Accepted Answer · 2019-01-14 11:14:46Z

3

In this specific case, it makes more sense to count:

MyModel.objects.filter(toss_winner=F('winner'), win_by_runs=0).count()

We here thus simply check how many MyModel records satisfy the given condition.

answered Jan 14, 2019 at 11:14

willeM_ Van Onsem

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8 Comments

Lax_Sam Over a year ago

So this condition is similar to checking whether MyModel.toss_winner = MyModel.winner and MyModel.win_by_runs = 0?

willeM_ Van Onsem Over a year ago

@Laxman: yes. We thus count the number of MyModel records, for which that condition holds.

Lax_Sam Over a year ago

Ok. One last question. How to check not equal to in django? Because according to my understanding there is no '!=' operator in django.

Lax_Sam Over a year ago

To check win_by_runs != 0 what should be the operator?

willeM_ Van Onsem Over a year ago

@Laxman: sorry, the arguments indeed should be swapped, so MyModel.objects.filter(~Q(win_by_runs=0), toss_winner=F('winner')).count().

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