我正在构建一个Django电子商务网站，并且在使用购物车功能时，我注意到每次尝试更改购物车中特定商品的数量时，购物车中的所有商品都会重新排序以不同的顺序。我想知道是否有什么办法可以在后端显示项目之前对其进行排序。
**仅当用户“经过身份验证”时，我才会收到此错误**访客结帐工作正常
这是我的购物车Views.py
def cart(request):
# Authenticated Checkout
if request.user.is_authenticated:
customer = request.user.customer
order, created = Order.objects.get_or_create(customer=customer, complete=False)
cartItems = order.get_cart_items
items = order.orderitem_set.all()
if cartItems == 0:
context = {"items": items, "order": order, "cartItems": cartItems}
return render(request, "cart_empty.html", context)
#Guest Checkout
else:
data = cartData(request)
cartItems = data["cartItems"]
order = data["order"]
items = data["items"]
if cartItems == 0:
context = {"items": items, "order": order, "cartItems": cartItems}
return render(request, "cart_empty.html", context)
context = {"items":items, "order": order, "cartItems":cartItems}
return render(request, "cart.html", context)
def update_cart(request):
data = json.loads(request.body)
productId = data["productId"]
action = data["action"]
customer = request.user.customer
product = Product.objects.get(id=productId)
order, created = Order.objects.get_or_create(customer=customer, complete=False)
orderItem, created = OrderItem.objects.get_or_create(order=order, product=product)
if action == "add":
orderItem.quantity = (orderItem.quantity + 1)
elif action == "reduce":
orderItem.quantity = (orderItem.quantity - 1)
orderItem.save()
if action == "remove":
orderItem = orderItem.delete()
return JsonResponse("item was added", safe=False)
这是我的JavaScript文件
// Getting the cart cookie Value stored in the browser
function getCookie(cname) {
var name = cname + "=";
var ca = document.cookie.split(';');
for(var i=0; i<ca.length; i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1);
if (c.indexOf(name) == 0) return c.substring(name.length,c.length);
}
return "";
}
var cart = JSON.parse(getCookie("cart"));
// Finding all the Minus buttons on the page and adding a click event listener to each one
const reduce_btn = document.getElementsByClassName("btn minus1 update-cart")
for (i = 0; i < reduce_btn.length; i++) {
reduce_btn[i].addEventListener("click", function(event){
var productId = this.dataset.id
var action = this.dataset.action
if (user === "AnonymousUser"){
addCookieItem(productId, action)
} else {
updateUserOder(productId,action)
}
})
}
// Finding all the Plus buttons on the page and adding a click event listener to each one
const increase_btn = document.getElementsByClassName("btn add1 update-cart")
for (i = 0; i < increase_btn.length; i++){
increase_btn[i].addEventListener("click", function(event){
var productId = this.dataset.id
var action = this.dataset.action
if (user === "AnonymousUser"){
addCookieItem(productId, action)
} else {
updateUserOder(productId,action)
}
})
}
// Finding all the remove buttons on the page and adding a click event listener to each one
const removeButton = document.getElementsByClassName("removeButton")
for (i = 0; i < removeButton.length; i++) {
removeButton[i].addEventListener("click", function(event){
var productId = this.dataset.id
var action = this.dataset.action
if (user === "AnonymousUser"){
removeFromCart(productId, action)
} else {
updateUserOder(productId,action)
}
})
}
// Removing the product from the order if the remove button is clicked
function removeFromCart(productId, action) {
if (action == 'remove'){
delete cart[productId];
}
document.cookie ='cart=' + JSON.stringify(cart) + ";domain=;path=/"
location.reload()
}
// (Guest Checkout) Updating the order of the customer if he is not authenticated
function addCookieItem(productId, action) {
console.log("not logged in..........")
if (action == 'add'){
cart[productId]['quantity'] += 1
}
if (action == 'reduce'){
cart[productId]['quantity'] -= 1
}
document.cookie ='cart=' + JSON.stringify(cart) + ";domain=;path=/"
location.reload()
}
// csrf token
var csrftoken = localStorage.getItem("csrftoken")
// (Authenticated Checkout) Updating the order of the customer if he is Authenticated
function updateUserOder(productId, action){
var url = "http://127.0.0.1:8000/update_cart/"
fetch(url, {
method: "POST",
headers: {
"Content-Type":"application/json",
"X-CSRFToken":csrftoken,
},
body:JSON.stringify({"productId": productId, "action": action})
})
.then((response) =>{
return response.json();
})
.then((data) => {
location.reload()
})
}
这是我的HTML文件
<!DOCTYPE HTML>
<html lang="en">
<head>
<meta charset="UTF-8" name="viewport" content="width=device-width, initial-scale=1.0">
<title>Cart</title>
<link rel="stylesheet" type="text/css" href="{% static 'css/cart.css' %}">
<script type="text/javascript">
var user = "{{request.user}}"
</script>
</head>
<body>
<!-- navigation menu -->
{% include "topnav.html" %}
<div class="maincontent">
<h1 class="hhh1" style="font-size:50px; margin:0px; margin-bottom:30px">Your Cart</h1>
<div class="centerblock">
<!-- DYNAMIC CONTENT GOES HERE -->
<div class="cart-row">
<span class="cart-item cart-header cart-column">ITEM</span>
<span class="cart-header cart-column">PRICE</span>
<span class="cart-quantity cart-header cart-column">QUANTITY</span>
</div>
<div class="cart-items">
{% for item in items %}
<div>
<div class="cart-item cart-column">
<img class="cart-item-image" src="{{item.product.imageURL}}" width="100" height="100">
<span class="cart-item-title">{{item.product.title}}</span>
</div>
<span class="cart-price cart-column" data-price="{{item.product.price}}" >£{{item.product.price}}</span>
<div class="cart-quantity cart-column">
<div class="quantity">
<button data-id={{item.product.id}} data-action="reduce" id="minus" class="btn minus1 update-cart" >-</button>
<input class="cart-quantity-input quantity" type="number" id="id_form-0-quantity" name="quantity" min="1" max="5" value="{{item.quantity}}">
<button data-id={{item.product.id}} data-action="add" id="plus" class="btn add1 update-cart" >+</button>
<button data-id={{item.product.id}} data-action="remove" class="removeButton" type="button">REMOVE</button>
</div>
</div>
</div>
{% endfor %}
<div class="cart-total">
<strong class="cart-total-title">Total</strong>
<span class="cart-total-price">£{{order.get_cart_total}}</span>
</div>
<div class="ordersummary">
<form action="checkout-info" method="post">
{% csrf_token %}
<input type="submit" value="CHECKOUT">
</form>
</div>
</div>
</div>
</div>
{% include "footer.html" %}
<script src="{% static 'js/test2.js' %}" ></script>
</body>
</html>
答案 0 :(得分：1)
假设您希望它们按照相反的顺序添加到购物车，则可以按其id字段对其进行排序：
items = order.orderitem_set.order_by('-id')