Django:访问ManytoMany字段

Question

我目前面临以下挑战。作为我页面的访问者，您可以在不同的事件之间进行选择。假设您点击了其中一个，现在您位于 id 1 的事件页面。您可以选择不同的门票。假设您选择了门票 1(100 美元)(含 19% 增值税)和门票 2(200 美元)(包括食品)，含 19% + 7% 增值税。现在您单击“ checkout ”，下一页将列出以下内容:

1x 门票 1 - 总计:100 美元

1x 门票 2 - 总计:200 美元

总计:300 美元

---

增值税 1 (19%):57 美元 (19 + 38)

增值税 2 (7%):14 美元

---

小计:229 美元

我现在正在这个多对多领域苦苦挣扎。您将如何访问各个门票，从相应的多对多字段中获取增值税，然后将它们显示在我的模板末尾？我考虑过元组、字典等，但我真的很难在这里找到最好的方法。您是否遇到过类似的代码挑战？

class TicketTax(models.Model):
    event = models.ForeignKey(
        Event,
        on_delete=models.PROTECT,
        related_name='ticket_taxes'
    )
    name = models.CharField(max_length=100)
    percentage = models.DecimalField(
        max_digits=5,
        decimal_places=4
    )
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)


class Ticket(models.Model):
    event = models.ForeignKey(
        Event,
        on_delete=models.PROTECT,
        related_name='tickets'
    )
    ticket_tax = models.ManyToManyField(TicketTax, blank=True)
    price_gross = models.DecimalField(
        max_digits=25,
        decimal_places=2
    )
    name = models.CharField(max_length=100)
    description = models.TextField(blank=True, null=True)
    start_at = models.DateTimeField()
    end_at = models.DateTimeField()
    quantity = models.PositiveIntegerField()
    status = models.CharField(
        max_length=8,
        choices=TicketStatus.CHOICES
    )
    is_archived = models.BooleanField(default=False)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

更新1:

reserved_item = ReservedItem.objects.filter(order_reference=session_order_reference)
tax_dict = {}
        for i in reserved_item:
            ticket_subtotal = i.ticket.price_gross * i.quantity

            taxes_for_this_ticket = i.ticket.ticket_tax.all()
            for taxes in taxes_for_this_ticket:
                amount_of_taxes = ticket_subtotal * taxes.percentage
                tax_dict[taxes] = amount_of_taxes

更新2(解决方案):

views.py

d = {}
    for i in reserved_item:
        ticket_subtotal = i.ticket.price_gross * i.quantity

        taxes_for_this_ticket = i.ticket.ticket_tax.all()

        for taxes in taxes_for_this_ticket:
            amount_of_taxes = ticket_subtotal * taxes.percentage

            if taxes in d:
                d[taxes] += amount_of_taxes
            else:
                d[taxes] = amount_of_taxes

    for key, value in d.items():
        print(key.name, " Value: ", value)

模板 - checkout.html:

{% for key, values in taxes.items %}
    <p>
        {{key.name}}<br>
        {{values}}
    </p>
{% endfor %}

Answer 1

假设ticket是一个Ticket对象，taxes_for_this_ticket = Ticket.ticket_tax.all()

应该适合你