Question 115892 in Mongodb Question posted in
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Mongodb – unsupported operand type(s) for +=: 'int' and 'Decimal128'

I’m trying to add the numbers from the MongoDB database.

meal_data = Data.objects.filter(year= se_year, month= se_month, category = 'Meal')
    meal_amt = 0
    for i in meal_data:
        id = i.id
        m_amount_data = Data.objects.get(id = id)
        meal_amt += m_amount_data.amount

TypeError: unsupported operand type(s) for +=: ‘int’ and ‘Decimal128’

The error is showing in this line.

meal_amt += m_amount_data.amount

I need to add those numbers and store them in a variable meal_amt.

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2

Answers


  1. 0

    change the type of meal_amt variable into Decimal.

    from decimal import Decimal

meal_data = Data.objects.filter(year= se_year, month= se_month, category = 'Meal')
meal_amt = Decimal(0)

for i in meal_data:
    meal_amt += i.amount

    Also, no need to fetch the Data object in for loop.

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  2. 0

    You can just use the aggregate function to get the total sum like so:

    from django.db.models import Sum

meal_amt = Data.objects.filter(
    year=se_year, 
    month=se_month, 
    category='Meal'
).aggregate(Sum('amount'))['amount__sum']

    This should have better performance comparing with what you’re already doing since we are not looping through the records but getting the sum straight from the database instead.

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