Django query sum values from related table - django

Question

I have two tables:
Ticket Table
id paid_with_tax
1 5
2 6
3 7
TicketAdjustment Table
id ticket_id value_with_tax
1 1 2
2 1 1
3 1 2
4 1 3
5 2 5
The query I use:
use = 0
Ticket.objects.all().annotate(
paid_amount=Sum(
F('paid_with_tax') +
Coalesce(F('ticketadjustment__value_with_tax'), 0) * use
)
)
the query would return the following:
[
{id: 1, paid_amount: 7},
{id: 1, paid_amount: 6},
{id: 1, paid_amount: 7},
{id: 1, paid_amount: 8},
{id: 2, paid_amount: 11},
{id: 3, paid_amount: 7},
]
but the above is incorrect since the Ticket Table id=1 values are duplicated by the TicketAdjustment Table values.
how can i get the query to sum the TicketAdjustment Table values and return the following:
[
{id: 1, paid_amount: 13},
{id: 2, paid_amount: 11},
{id: 3, paid_amount: 7},
]

Answer 1

Here the solution for your problem :
Ticket.objects.all().annotate(
paid_amount=(F('paid_with_tax') +
Sum(Coalesce(F('ticketadjustment__value_with_tax'), 0))
)
).values_list('id', 'paid_amount')
values_list select the field you want in your result.
In your primary request there is a big problem.
Sum(F('paid_with_tax') + Coalesce(F('ticketadjustment__value_with_tax'), 0) * use)
This ligne miltiply value_with_tax with zero. So give you zero. It's like :
Sum(F('paid_with_tax'))
You want the sum of value_with_tax for each ticket, this is why I move Sum on it :
Sum(Coalesce(F('ticketadjustment__value_with_tax'), 0))
And after add the value of paid_with_tax
NB : I remove your variable use, because don't know is goal.