Django 从 OneToOneField 中只删除一个对象并检索它

Question

我正在使用 Django 构建一个简单的网站，用户可以在其中购买购物车。他们可以将商品添加到购物车，然后他们可以购买它们（将购买的商品添加到另一个模型）。好吧，我是 Django 的新手，我有一个问题。购买产品后，我删除了购物车对象并创建了另一个空的购物车对象。第一次买东西没问题，第二次就想付款了。我总是得到空的购物车对象，尽管如果我检查数据库，我可以看到那里有合适的产品...

我将在这里留下我的 django 模型：

from __future__ import unicode_literals

from django.db import models
from django.contrib.auth.models import User

class Cart(models.Model):
    user = models.ForeignKey(User, null=True)
    items = models.ManyToManyField(Item, null=True)
    money = models.FloatField(default=0)
    def __str__(self):
        aux = ""
        for item in self.items.all():
            aux += "\n"+"["+item.name+"]" + str(item.price)+ " " + item.type + " " + str(item.description)+"\n"
        aux += "\n\nTotal Price: "+str(self.money)
        return aux

class Client(models.Model):
    user = models.OneToOneField(User)
    cart = models.OneToOneField(Cart, null=True, on_delete=models.SET_NULL)
    money = models.FloatField(default=0)
    def __str__(self):
        return "["+str(self.user)+"]"+str(self.money)

还有我的支付、购买和添加功能：

@login_required
def addCart(request):
    selectedItems =[]
    for key in request.POST:
         if key.startswith("checkbox"):
             identificador = int(request.POST[key])
             item = Item.objects.get(id=identificador)
             client = Client.objects.get(user=request.user.id)
             if client.cart == None:
                 user = User.objects.get(username=request.user.username)
                 cart = Cart.objects.create(user=user)
                 client.cart = cart
                 client.cart.items.add(item)
                 client.cart.money += item.price
                 client.cart.save()
             else:
                 client.cart.items.add(item)
                 client.cart.money += item.price
                 client.cart.save()
    return HttpResponseRedirect(request.META["HTTP_REFERER"])

@login_required
def buy(request):
    client = Client.objects.get(user=request.user.id)
    if client.cart != None:
        products = client.cart.items
        total = client.cart.money
    else:
        products = client.cart
        total = 0
    context = {
        'cart':products,
        'money':total
    }
    return render(request, 'mediacloud/buy.html', context)

def pay(request):
    client = Client.objects.get(user=request.user.id)
    products = client.cart.items.all()
    result = False
    if client.money >= client.cart.money:
        client.money -= client.cart.money
        client.save()
        client.cart.money = 0.0
        client.cart.save()
        for product in products:
            Purchases.objects.create(item=product, user=str(request.user))
            result = True
        user = User.objects.get(username=request.user.username)
        Cart.objects.filter(user=user).delete()
        cart = Cart.objects.create(user=user)
        client.cart = cart
        client.cart.save()
    context = {
        'result':result
    }
    return render(request, 'mediacloud/result.html', context)

我不明白为什么我没有从客户的购物车中取回任何商品...用户第一次向购物车添加东西时一切正常，当我删除购物车对象并为用户创建一个新的购物车对象也许我把我的模型弄错了......如果有人能指出我正确的方向，我将不胜感激

Answer 1

因为您实际上是在尝试清除购物车中的商品，而不是删除 Cart 对象并重新创建它。尝试将 ManyToManyField 清除到 Cart 对象上的项目：

Cart.objects.filter(user=user)[0].items.clear()

Django 从 OneToOneField 中只删除一个对象并检索它

Django Deleting just one object from OneToOneField and retrieve it

python

django

models

one-to-one