CODEWITHSUNDEEP
djangodjango-modelsmany-to-many
yasar
yasar

Reputation: 13748

Django, sum of fields in intermediary model with given queryset

I have 2 models, one of them has many to many relation with itself through other table like this.

class a(models.Model):
    # fields
class b(models.Model):
    from_a = models.ForeignKey(a)
    to_a = models.ForeignKey(a)
    count = models.PositiveIntegerField()

Now, what I wonder is, what is the best way of calculating sum of counts in b's where from_a is "something". This one seems trivial, but I can't figure it out.

Upvotes: 1

Views: 360

Answers (1)

Daniel Roseman
Daniel Roseman

Reputation: 599620

from django.db.models import Sum
b.objects.filter(from_a__whatever='something').aggregate(Sum('count'))

Upvotes: 3

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