与Django Orm进行查询？

Question

我已经使用此代码进行查询：

views.py：

        reservations_table = Reservation.objects.all()

        total_commission = 0

        for reservation in reservations_table:
            for city in COMMISSION_RATES.keys():
                if reservation.city == city.upper():
                    total_commission += reservation.net_income * COMMISSION_RATES[city] / 100

        for reservation in reservations_table:
            for month in COMMISSION_PER_MONTH:
                if reservation.checkout.month == month:
                    reservation.monthly = COMMISSION_PER_MONTH[month]

        for reservation in reservations_table_city:
            commission_amount_city += reservation.net_income * COMMISSION_RATES[form.cleaned_data['city']] / 100

models.py：

from django.db import models


class Reservation(models.Model):
    reservation_code = models.CharField(max_length=150,unique=True)
    checkin = models.DateField()
    checkout = models.DateField()
    flat = models.CharField(max_length=150)
    city = models.CharField(max_length=150)
    net_income = models.DecimalField(max_digits=10, decimal_places=2)

    def __str__(self):
        return self.reservation_code

startants.py：

COMMISSION_RATES = {
    'LONDON': 10,
    'PARIS': 12,
    'PORTO': 9,
}

如何进行查询但使用只有django orm？因此，有3个疑问可行，但是想法是使它们全部django orm。

Answer 1

您可以尝试这样的事情。 小心，我的代码可能包含错误，这是解决问题的唯一方法。

reservations_table = Reservation.objects.filter(
    city__in=COMMISSION_RATES.keys(),
).annotate(
    instance_commission=F('net_income') * COMMISSION_RATES[F('city')] / Value(100),
).aggregate(
    total_commission=Sum('instance_commission')
)