使用Django ORM进行查询?

Question

我使用以下代码进行查询:

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

constants.py:

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

如何做一个查询，但只使用Django ORM?因此，有3个查询可以工作，但我们的想法是使它们都是Django ORM。

Answer 1

您可以尝试这样做。小心，我的代码可能包含错误，这是唯一的方法来解决你的问题。

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')
)