Django清除导致save（）被禁止的数据，以防止由于相关对象未保存而导致数据丢失

Question

我需要知道如何清除导致以下错误的未保存的相关数据：

禁止保存（）以防止由于未保存的相关对象'order'而导致数据丢失。

我的代码按预期工作，但我未能完成一个订单。此后，任何保存新订单的尝试都会导致上述错误。我知道原因是对django.db.models.base.py的更改，但肯定有一些方法可以通过日志之类的方式清除这些更改...我尝试重新创建数据库和sqlflush命令，但都不起作用。

视图

# -*- coding: utf-8 -*-
from __future__ import unicode_literals
import weasyprint
from django.shortcuts import render, redirect, get_object_or_404
from django.contrib.admin.views.decorators import staff_member_required
from django.core.urlresolvers import reverse
from django.conf import settings
from django.http import HttpResponse
from django.template.loader import render_to_string
from .models import OrderItem, Order
from .forms import OrderCreateForm
from cart.cart import Cart
from .tasks import order_created
# Create your views here.
@staff_member_required
def admin_order_detail(request, order_id):
    order = get_object_or_404(Order, id=order_id)
    return render(request, 'admin/orders/order/detail.html', {'order': order})

@staff_member_required
def admin_order_pdf(request, order_id):
    order = get_object_or_404(Order, id=order_id)
    html = render_to_string('orders/order/pdf.html', {'order': order})
    response = HttpResponse(content_type='application/pdf')
    response['Content-Disposition'] = 'filename="order_{}.pdf"'.format(order.id)
    weasyprint.HTML(string=html).write_pdf(response, stylesheets=[weasyprint.CSS(settings.STATIC_ROOT + 'css/pdf.css')])

    return response


def order_create(request):
    cart = Cart(request)
    if request.method == 'POST':
        form = OrderCreateForm(request.POST)
        if form.is_valid():
            order = form.save(commit=False)
            if cart.coupon:
                order.coupon = cart.coupon
                order.discount = cart.coupon.discount
                order.save()
            for item in cart:
                OrderItem.objects.create(order=order, product=item['product'], price=item['price'], quantity=item['quantity'])
            #emptying the cart
            cart.clear()
            #launch celery async task
            order_created.delay(order.id)
            request.session['order_id'] = order.id #set order.id session
            return redirect(reverse('payment:process'))
    else:
        form = OrderCreateForm()
    return render(request, 'orders/order/create.html', {'cart': cart, 'form':form})

模型

class Order(models.Model):
    first_name = models.CharField(_('first_name'),max_length=50)
    last_name = models.CharField(_('last_name'),max_length=50)
    email = models.EmailField(_('email'),)
    address = models.CharField(_('address'),max_length=250)
    postal_code = models.CharField(_('postal_code'),max_length=250)
    city = models.CharField(_('city'),max_length=100)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    paid = models.BooleanField(default=False)
    coupon = models.ForeignKey(Coupon, related_name='orders', null=True, blank=True)
    discount = models.IntegerField(default=0, validators=[MinValueValidator(0), MaxValueValidator(100)])

    class Meta:
        ordering = ('-created',)

    def __unicode__(self):
        return 'Order {}'.format(self.id)

    def get_total_cost(self):
        total_cost  = sum(item.get_cost() for item in self.items.all())
        return total_cost - total_cost *(self.discount)

class OrderItem(models.Model):
    order = models.ForeignKey(Order, related_name='items')
    product = models.ForeignKey(Product, related_name='order_items')
    price = models.DecimalField(max_digits=10, decimal_places=2)
    quantity = models.PositiveIntegerField(default=1)

    def __unicode__(self):
        return '{}'.format(self.id)

    def get_cost(self):
        return self.price * self.quantity

表格

from django import forms
from .models import Order


class OrderCreateForm(forms.ModelForm):
    class Meta:
        model = Order
        fields = ['first_name', 'last_name', 'email', 'address', 'postal_code', 'city']

Answer 1

如果检查模型，则可以看到order表中的coupon字段是一个外键，换句话说，是一个相关的对象。

因为不保存优惠券对象，所以它没有PK，并且不能添加到顺序中。首先保存coupon对象，然后将其添加到订单中。

所以类似于：

coupon = cart.coupon # not sure if this in between step is needed
coupon.save()
order.coupon = coupon
order.save()