Django - add-up Sum of multiple model fields

Question

How can i add-up the Sum of each Model here? In the end i simply want to have one single value for all up_votes /down_votes accross all 3 models. See example below:

def calc_user_feedback():
    users = User.objects.all()
    try:
        for user in users:
            fed_qry_up_votes = Model1.objects.filter(author=user).aggregate(Sum('up_vote')) + \
                               Model2.objects.filter(author=user).aggregate(Sum('up_vote')) + \
                               Model3.objects.filter(author=user).aggregate(Sum('up_vote'))
            fed_qry_down_votes = Model1.objects.filter(author=user).aggregate(Sum('down_vote')) + \
                               Model2.objects.filter(author=user).aggregate(Sum('down_vote')) + \
                               Model3.objects.filter(author=user).aggregate(Sum('down_vote'))

            logger.info("Overall user feedback calculated successfully.")
    except:
        logger.info("Error processing task: 'Calculate user feedback', please investigate")

Why exactly did you make three models? If two things are that similar, it is often useful to use the same model. — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Jan 22, 2020 at 21:00
I absolutly with you, but my application has several very complex implementation and i was sadly not able to stay confirm. Im not able to change everything afterward as the code has started like that years ago ... — user11684966
– user11684966, Commented Jan 22, 2020 at 21:15

alissongranemann · Accepted Answer · 2020-01-22 21:56:02Z

1

Assuming author has no related_name set on each model:

from django.db.models import F, Sum

users = (
    User.objects.annotate(up_votes_1=Sum("model1_set__up_vote"))
    .annotate(up_votes_2=Sum("model2_set__up_vote"))
    .annotate(up_votes_3=Sum("model3_set__up_vote"))
    .annotate(total=F("up_votes_1") + F("up_votes_2") + F("up_votes_3"))
)

Now you can iterate over users and get a total for each one.

answered Jan 22, 2020 at 21:56

alissongranemann

9929 silver badges13 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

user11684966 Over a year ago

But it also seems that i only get back the number of objects not the number of the actual up_vote/down_vote field if i use count

alissongranemann Over a year ago

You don't need to use count, just use the total field.

Collectives™ on Stack Overflow

Django - add-up Sum of multiple model fields

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related