Django annotate: sum all records by asset | only one table

Question

My django model:

class Movimentacao(models.Model):
    product = models.CharField(max_length=300)
    value = models.DecimalField(max_digits=19, decimal_places=2)

I'm trying to SUM all value by product using django annotate. I tried:

query = Movimentacao.objects.annotate(total=Sum('value')
                                    ).values('product', 'total'
                                    ).order_by('product')

There are a lot of repeated products (multiple lines) with different values and I'd like to group all same products and sum their respective values.

But it's showing all records without grouping and summing all of them.

I wouldn't like to use aggregate in this case.

Tks

Answer 1

You use .values(…) ^[Django-doc] first:

from django.db.models import Sum

query = (
    Movimentacao.objects.values('product')
    .annotate(total=Sum('value'))
    .order_by('product')
)

That being said, if the same product occurs multiple times, it is normally best practice to make a Product model and work with a ForeignKey.