产品变体未反映 Django 电子商务项目中订单摘要中的更新数量

Question

我对订单摘要页面中相关的变体和数量有疑问。

当我将 2 件商品添加到购物车时：

• 商品 X 尺寸小 数量：1
• 商品 X 中号 数量：1

当我更改 item X size medium 的数量时，此更改反映在 item X size small 中，这是首先选择的。

变成这样：

• 商品 X 尺寸小 数量：2
• 商品 X 中号 数量：1

在订单汇总中，模板中有加号和减号，可以改变数量。

我最近明白了这一点，因为模板中没有表单。将带有表单数据的 POST 请求发送到添加到购物车视图的代码不存在，因为 item_var 将始终是一个空列表，因此 order_item.variation.add(*item_var) 什么都不做。我不知道如何向这个模板添加 POST 请求。

在模板中有一个 URL to add-to-cart”，但是 URL 是通过 GET 传输的，所以 if request.method == 'POST': 之后的代码永远不会命中。此外，即使它会， add_to_cart url 对变化一无所知，因为它只获取项目 slug。

这是模板：

    <main>
        <div class="container">
        <div class="table-responsive text-nowrap" style="margin-top:90px">
        <h2> Order Summary</h2>
        <table class="table">
            <thead>
            <tr>
                <th scope="col">#</th>
                <th scope="col">Item Title</th>
                <th scope="col">Price</th>
                <th scope="col">Quantity</th>
                <th scope="col">Size</th> 
                <th scope="col">Total Item Price</th>
            </tr>
            </thead>
            <tbody>
            {% for order_item in object.items.all %}
            <tr>
                <th scope="row">{{ forloop.counter }}</th>
                <td>{{ order_item.item.title }}</td>
                <td>{{ order_item.item.price }}</td>
                <td>
                <a href="{% url 'core:remove-single-item-from-cart' order_item.item.slug %}"><i class="fas fa-minus mr-2"></a></i>
                {{ order_item.quantity }}
                <a href="{% url 'core:add-to-cart' order_item.item.slug %}"><i class="fas fa-plus ml-2"></a></i>
                </td>                
                <td>
                {% if order_item.variation.all %}
                {% for variation in order_item.variation.all %}
                {{ variation.title|capfirst }}
                {% endfor %}
                {% endif %}
                </td> 
                <td>
                {% if order_item.item.discount_price %}
                    $ {{ order_item.get_total_discount_item_price }}
                    <span class="badge badge-primary" style="margin-left:10px">Saving ${{ order_item.get_amount_saved }}</span>
                {% else %}
                    $ {{ order_item.get_total_item_price }}
                {% endif %}
                <a style="color:red" href="{% url 'core:remove-from-cart' order_item.item.slug %}">
                <i class="fas fa-trash float-right"></i>
                </a>
                </td>
            </tr>
            {% empty %}
            <tr>
                <td colspan='5'>Your Cart is Empty</td>
            </tr>
            <tr>
                <td colspan="5">
                <a class='btn btn-primary float-right ml-2'href='/'>Continue Shopping</a>
            </tr>                
            {% endfor %}
            {% if object.coupon %}
            <tr>
                <td colspan="4"><b>Coupon</b></td>
                <td><b>-${{ object.coupon.amount }}</b></td>
            </tr>            
            {% endif %}
            <tr>
                <td colspan="5"><b>Sub total</b></td>
                <td><b>${{ object.get_total }}</b></td>
            </tr>
            <tr>
                <td colspan="5">Taxes</td>
                <td>${{ object.get_taxes|floatformat:2  }}</td>
            </tr>
            {% if object.grand_total %}
            <tr>
                <td colspan="5"><b>Grand Total</b></td>
                <td><b>${{ object.grand_total|floatformat:2 }}</b></td>
            </tr>
            <tr>
                <td colspan="6">
                <a class='btn btn-primary float-right ml-2'href='/'>Continue Shopping</a>
                <a class='btn btn-warning float-right'href='/checkout/'>Proceed to Checkout</a></td>
            </tr> 
            {% endif %}                          
            </tbody>
        </table>
        </div>
        </div>
    </main>

这里是views.py

class OrderSummaryView(LoginRequiredMixin, View):
    def get(self, *args, **kwargs):

        try:
            order = Order.objects.get(user=self.request.user, ordered=False)
            context = {
                'object': order
            }
            return render(self.request, 'order_summary.html', context)
        except ObjectDoesNotExist:
            messages.warning(self.request, "You do not have an active order")
            return redirect("/")


@login_required
def add_to_cart(request, slug):
    item = get_object_or_404(Item, slug=slug)

    order_item_qs = OrderItem.objects.filter(
        item=item,
        user=request.user,
        ordered=False
    )

    item_var = []  # item variation
    if request.method == 'POST':
        for items in request.POST:
            key = items
            val = request.POST[key]
            try:
                v = Variation.objects.get(
                    item=item,
                    category__iexact=key,
                    title__iexact=val
                )
                item_var.append(v)
            except:
                pass

        if len(item_var) > 0:
            for items in item_var:
                order_item_qs = order_item_qs.filter(
                    variation__exact=items,
                )

    if order_item_qs.exists():
        order_item = order_item_qs.first()
        order_item.quantity += 1
        order_item.save()
    else:
        order_item = OrderItem.objects.create(
            item=item,
            user=request.user,
            ordered=False
        )
        order_item.variation.add(*item_var)
        order_item.save()

    order_qs = Order.objects.filter(user=request.user, ordered=False)
    if order_qs.exists():
        order = order_qs[0]
        # check if the order item is in the order
        if not order.items.filter(item__id=order_item.id).exists():
            order.items.add(order_item)
            messages.info(request, "This item quantity was updated.")
            return redirect("core:order-summary")
    else:
        ordered_date = timezone.now()
        order = Order.objects.create(
            user=request.user, ordered_date=ordered_date)
        order.items.add(order_item)
        messages.info(request, "This item was added to cart.")
        return redirect("core:order-summary")


@login_required
def remove_from_cart(request, slug):
    item = get_object_or_404(Item, slug=slug)
    order_qs = Order.objects.filter(
        user=request.user,
        ordered=False
    )
    if order_qs.exists():
        order = order_qs[0]
        # check if the order item is in the order
        if order.items.filter(item__slug=item.slug).exists():
            order_item = OrderItem.objects.filter(
                item=item,
                user=request.user,
                ordered=False
            )[0]
            order.items.remove(order_item)
            order_item.delete()
            messages.info(request, "This item was removed from your cart")
            return redirect("core:order-summary")

        else:
            messages.info(request, "This item was not in your cart")
            return redirect("core:product", slug=slug)
    else:
        messages.info(request, "You don't have an active order")
        return redirect("core:product", slug=slug)


@login_required
def remove_single_item_from_cart(request, slug):
    item = get_object_or_404(Item, slug=slug)
    order_qs = Order.objects.filter(
        user=request.user,
        ordered=False
    )
    if order_qs.exists():
        order = order_qs[0]
        # check if the order item is in the order
        if order.items.filter(item__slug=item.slug).exists():
            order_item = OrderItem.objects.filter(
                item=item,
                user=request.user,
                ordered=False
            )[0]
            if order_item.quantity > 1:
                order_item.quantity -= 1
                order_item.save()
            else:
                order.items.remove(order_item)
            messages.info(request, "This item quantity was updated")
            return redirect("core:order-summary")
        else:
            messages.info(request, "This item was not in your cart")
            return redirect("core:product", slug=slug)
    else:
        messages.info(request, "You do not have an active order")
        return redirect("core:product", slug=slug)

这里是models.py

class Item(models.Model):
    title             = models.CharField(max_length=100)
    -------------------------------------------------------------------------
    updated           = models.DateTimeField(auto_now_add=False, auto_now=True)
    active            = models.BooleanField(default=True)

    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse("core:product", kwargs={
            'slug': self.slug
        })

    def get_add_to_cart_url(self):
        return reverse("core:add-to-cart", kwargs={
            'slug': self.slug
        })

    def get_remove_from_cart_url(self):
        return reverse("core:remove-from-cart", kwargs={
            'slug': self.slug
        })


class VariationManager(models.Manager):
    def all(self):
        return super(VariationManager, self).filter(active=True)

    def sizes(self):
        return self.all().filter(category='size')

    def colors(self):
        return self.all().filter(category='color')


VAR_CATEGORIES = (
    ('size', 'size',),
    ('color', 'color',),
    ('package', 'package'),
)


class Variation(models.Model):
    item = models.ForeignKey(Item, on_delete=models.CASCADE)
    category = models.CharField(
        max_length=120, choices=VAR_CATEGORIES, default='size')
    title = models.CharField(max_length=120)
    image = models.ImageField(null=True, blank=True)
    price = models.DecimalField(
        decimal_places=2, max_digits=100, null=True, blank=True)
    objects = VariationManager()
    active = models.BooleanField(default=True)

    def __str__(self):
        return self.title

class OrderItem(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL,
                             on_delete=models.CASCADE)
    ordered = models.BooleanField(default=False)
    item = models.ForeignKey(Item, on_delete=models.CASCADE)
    quantity = models.IntegerField(default=1)
    variation = models.ManyToManyField(Variation)

    def __str__(self):
        return f"{self.quantity} of {self.item.title}"

网址.py

app_name = 'core'

urlpatterns = [
    path('', HomeView.as_view(), name='home'),
    path('order-summary/', OrderSummaryView.as_view(), name='order-summary'),
    path('product/<slug>/', ItemDetailView.as_view(), name='product'),
    path('add-to-cart/<slug>/', add_to_cart, name='add-to-cart'),
    path('remove-item-from-cart/<slug>/', remove_single_item_from_cart,
         name='remove-single-item-from-cart'),
    path('remove-from-cart/<slug>/', remove_from_cart, name='remove-from-cart'),
]

Answer 1

当然，对于 django 来说，这两个项目都是一样的。

对此负责的行是：

if order_item_qs.exists():
    order_item = order_item_qs.first()  # Here, you are always picking the first item that your filter returned, see: https://docs.djangoproject.com/en/dev/ref/models/querysets/#first
    order_item.quantity += 1
    order_item.save()

取自https://docs.djangoproject.com/en/dev/ref/models/querysets/#first：

first()¶

返回查询集匹配的第一个对象，如果有，则返回 None 没有匹配的对象。如果 QuerySet 没有定义排序，则 queryset 按主键自动排序。这可能会影响 聚合结果，如与默认排序的交互中所述 或 order_by()。

然而，罪魁祸首是：

order_item_qs = OrderItem.objects.filter(
    item=item,
    user=request.user,
    ordered=False
)

您想将变体传递给它，例如

order_item_qs = OrderItem.objects.filter(
    item=item,
    user=request.user,
    ordered=False,
    variation=variation
)

您可以考虑将尺寸添加为产品的一个字段，并根据变体创建单个产品。但是，简单地检索变化并确保仅通过将正确的项目传递给 filter() 来增加正确的项目也是一种正确的方法。

Answer 2

order_item_qs = order_item_qs.filter(
            Q(item_variations__exact=v)
        )

with:
order_item_qs = order_item_qs.filter(item_variations__variation=v)

Answer 3

我认为是块问题

if order_item_qs.exists():
        order_item = order_item_qs.first()
        order_item.quantity += 1
        order_item.save()

这段代码只执行一次 您需要将其重写为

if len(item_var) > 0:
   for items in item_var:
      order_item_qs = OrderItem.objects.filter(
        item=item,
        user=request.user,
        ordered=False
    ).filter(variation__exact=items,)

      if order_item_qs.exists():
          order_item = order_item_qs.first()
          order_item.quantity += 1
          order_item.save()
      else:
          order_item = OrderItem.objects.create(
             item=item,
            user=request.user,
            ordered=False
        )
          order_item.variation.add(*item_var)
          order_item.save()
    ```