django-paypal如何检查付款是否完成

Question

我使用django-paypal进行有效的付款方式，但是，如何在完成付款后重定向用户后如何检查付款是否实际完成？ 这是我基于process_payment函数的视图：

def payment_process(request, trade_id):
    trade = get_object_or_404(Trade, id=trade_id)
    host = request.get_host()

    paypal_dict = {
         ...
        'notify_url': 'https://{}{}'.format(host,
                                           reverse('paypal-ipn')),
        'return_url': 'https://{}{}/{}'.format(host,
                                           *reverse('payment_done', kwargs={'trade_id': trade.id})),
        'cancel_return': 'https://{}{}'.format(host,
                                              reverse('home')),
    }

    form = PayPalPaymentsForm(initial=paypal_dict)
    return render(request, 'payment/payment_process.html', {'trade': trade, 'form': form})

我的payment_done视图（付款后用户重定向到该视图：

# if paymenis done ????????:
      messages.success(request, 'Your product is in your inbox now')
      return redirect('trade:inbox')
# else (the payment was not completed
       messages.error(request, 'You didnt complete the payment, if you are sure you did contact us at someemail@gmail.com and provide us with some evidence')
       return redirect('home')