Django ORM, Sum column values through query

Question

I have a table with the following values:

user	amount	date
John	10	2017-07-01
John	20	2019-07-01
John	30	2020-09-01
John	40	2021-11-01
...	...	...
Dan	-20	2019-02-01
Dan	-30	2020-04-01
Dan	-40	2021-06-01

The input of the function is a range of date, for example, as follows:

date_start = '2019-01-01'
date_end = '2021-11-07'

Expected output:

For all users, for each date in this range of date, I want to return the sum of the amounts, from the current date to all previous dates like this:

user	amount	date
John	30 (10+20)	2019-07-01
John	60 (10+20+30)	2020-09-01
John	100 (10+20+30+40)	2021-11-01
...	...	...
Dan	-20	2019-02-01
Dan	-50 (-20-30)	2020-04-01
Dan	-90 (-20-30-40)	2021-06-01

My efforts

def get_sum_amount(self, date_start=None, date_end=None):
    date_detail = {}
    # Minimum date
    if date_start:
        date_detail['date__gt'] = date_start

    # Maximum date
    if date_end:
        date_detail['date__lt'] = date_end

    detail = Financial.objects.filter(Q(**date_detail)) \
        .values('user') \
        .annotate(sum_amount=Coalesce(Sum(F('amount')), Value(0)))

but no result.

UPDATED

The output of the function for the above example is:

user	amount
John	100
Dan	-90

Answer 1

You can use Window functions with a partition onuser to run a cumulative sum per user, ordered by the date:

detail = Financial.objects.filter(**date_detail).annotate(
    running_amount=Window(
        expression=Sum('amount'),
        partition_by=[F('user')],
        order_by=F('date').asc(),
    )
)