在 for 循环中组合过滤器结果

Question

我正在使用 Django 创建一个网站。我想组合多个过滤结果（查询集）。

我的模特关系

'员工' 1:m '会员' 1:m 'PaymentHistory' 1:1 'RefundHistory'

我的观点.py：

wanted_refund = set()
for m in staff.members.all():
    payment = m.PaymentHistory.filter(division="Membership")
    for p in payment:
        try:
            refund = RefundHistory.objects.filter(payment=p).filter(refund_date__range=[this_month_start, date])

            wanted_refund.add(refund)
        except RefundHistory.DoesNotExist:
            pass
 context = {
             'wanted_refund' : wanted_refund,}
    return render(request, 'refund.html', context)

但是，使用过滤器不起作用。它只在我使用 'get' 时有效。

print(refund) 显示如下结果：

 < QuerySet [] >

 < QuerySet [] >

 < QuerySet [] >

 < QuerySet [< RefundHistory: RefundHistory object >] >

我只想使用具有对象的查询集，我想要的是模板中的以下查询集：

{% for refund in wanted_history %}
 {{ refund.refund_date }}
 {{ refund.refund_amount}}
 {% endfor %}

如何在 for 循环中传递多个过滤器结果？

Answer 1

您可以使用管道运算符加入查询集：

wanted_refund = RefundHistory.objects.none()
for m in staff.members.all():
    payment = m.PaymentHistory.filter(division="Membership")
    for p in payment:
        try:
            wanted_refund |= RefundHistory.objects.filter(payment=p).filter(refund_date__range=[this_month_start, date])
        except RefundHistory.DoesNotExist:
            pass
wanted_refund = wanted_refund.distinct()
context = {'wanted_refund': wanted_refund}
return render(request, 'refund.html', context)

另外，如果它适合您，您可以使用 wanted_refund.update(list(refund)) 代替 wanted_refund.add(refund)

Answer 2

使用RefundHistory的单个查询可以获取每个会员每次付款的退款历史记录：

payments = []
for m in staff.members.all():
    payments.extend(m.PaymentHistory.filter(division="Membership").values_list('pk', flat=True))

wanted_refund = RefundHistory.objects.filter(payment__pk__in=payments, refund_date__range=[this_month_start, date])

context = {'wanted_refund' : wanted_refund,}
return render(request, 'refund.html', context)