使用服务的数据绑定不适用于 Angular JS

Question

我正在尝试使用Angular JS服务创建一个购物车。此服务称为用户购物车。UserCart 服务由两个变量组成，一个用于维护购物车总值，另一个用于存储添加到购物车中的项目。它还包含两个用于在购物车中添加或删除商品的功能。

UserCart 服务返回一个对象，该对象具有两个函数(添加/删除产品)和购物车总值。

在视图(末尾的html代码)中，每个产品(目前是衬衫和葡萄酒)都有"添加到购物车"按钮，单击该按钮时应调用产品控制器的函数"addToCart"，然后应更新UserCart的total_cart_val(正如我从控制台日志中确认的那样)。但是，该值不会反映在 HTML 中。

代码有什么明显的问题吗？

用户购物车.js如下：

(function() {
// Get reference to the app
var app = angular.module("jargoViewer");
// Create the factory that share the User Cart with various controllers
app.factory('UserCart', function(){
var cart_items = [];
var total_cart_val = 0;

var addProductInCart = function(prodID, prodCostPerUnit, prodQuantity) {
if((prodID in cart_items)) {
// true if "prodID" exist in cart_items
// Add the new prodID key element now
prodObj = cart_items[prodID];
prodObj.Quantity = prodObj.Quantity + prodQuantity;
} else {
// A product with same key already exists
cart_items[prodID] = {
'Quantity' : prodQuantity,
'CostPerUnit' : prodCostPerUnit
};
}
// Add the total newly added products cost to Total Cart Value
total_cart_val += prodCostPerUnit * prodQuantity;
}

var removeProductInCart = function(prodID, prodQuantity) {
if((prodID in cart_items)) {
// true if "prodID" exist in cart_items
// Add the new prodID key element now
prodObj = cart_items[prodID];
existingQuantity = prodObj.Quantity;
if(prodQuantity > existingQuantity) {
alert('No more of this item exists in the cart!');
} else {
prodObj.Quantity = prodObj.Quantity - prodQuantity;
// Add the total newly added products cost to Total Cart Value
total_cart_val -= prodCostPerUnit * prodQuantity;
if(prodObj.Quantity < 1) {
// No more of this product left in cart, remove from cart list
cart_items.splice(prodID, 1);
}
}
} else {
// Error
alert('No more of this item exists in the cart!');
}
}

// Return the Interface of UserCart
return { 
// products_in_cart: cart_items,
cart : {
cart_val : total_cart_val
},
addProdInCart : addProductInCart,
delProdInCart : removeProductInCart
};
});
}());

我的产品控制器.js是这样的

(function() {
var app = angular.module("jargoViewer");
//var ProductController = function($scope) {
var ProductController = function($scope, UserCart) {
$scope.addToCart = function(prodID, costPerUnit, quantity) {
UserCart.addProdInCart(prodID, costPerUnit, quantity);
}

$scope.products = [
{
'title' :   'First Product',
'id'    :   100001,
'img'   : 'product/shirt.jpg',
'cost'  : 899,
'sizes' : [
{
'label' :'Small'
},
{
'label' :'Medium'
}
]
},
{
'title' : 'Second Product',
'img'   : 'product/wine.png',
'id'    : 100002,
'cost'  : 3150,
'sizes' : [
{
'label' :'Small'
},
{
'label' :'Large'
}
]
}
];

$scope.userCart = UserCart.cart;
};

app.controller("ProductController", ProductController);
}());

我的观点如下。

<section class="big-product">
<div class="container">
<div class="row top30" ng-repeat="prod in products">
<span>&nbsp</span>
<div>
<div class="col-sm-4 product">
<!--<img src="product/shirt.jpg" alt="t-shirt" class="img-responsive">-->
<img src="{{prod.img}}" alt="t-shirt" class="img-responsive">
</div>
<div class="col-sm-8 info">
<div class="info-wrapper"  >
<h2>{{prod.title}}</h2>
<p class="lead">
{{prod.desc}}
</p>
<ul class="list-inline">
<li>
<div class="dropdown">
<button class="btn btn-default dropdown-toggle" type="button" id="menu1" data-toggle="dropdown">
Size
<span class="caret"></span>
</button>
<ul class="dropdown-menu" role="menu" aria-labelledby="menu1">
<li role="presentation" ng-repeat="prop in prod.sizes"><a role="menuitem" tabindex="-1" href="#">{{prop.label}}</a></li>
<!--<li role="presentation"><a role="menuitem" tabindex="-1" href="#">Medium</a></li>
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">Large</a></li>-->
</ul>
</div>
</li>
<li>
<div class="dropdown">
<button class="btn btn-default dropdown-toggle" type="button" id="menu1" data-toggle="dropdown">
Quantity
<span class="caret"></span>
</button>
<ul class="dropdown-menu" role="menu" aria-labelledby="menu1">
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">1</a></li>
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">2</a></li>
<li role="presentation"><a role="menuitem" tabindex="-1" href="#">3</a></li>
</ul>
</div>
</li>
<li class="currency">
{{prod.cost}}
</li>
<li class="Total Cart Value">
{{userCart.cart_val}}
</li>
</ul>
</div>
<a class="btn btn-success btn-unique" ng-click = "addToCart(prod.id, prod.cost, 1)">Add to Cart<i class="icon-cart-1"></i></a>
</div>
</div>
<span>&nbsp</span>
</div>
</div>
</section>

Answer 1

在这里发布我的 IRC 答案：

total_cart_val是一个基元，因此当您将其分配给cart.cart_val时，您是在分配值而不是对变量的引用。由于您更新的是total_cart_val变量而不是cart.cart_val属性，因此更改不会反映在导出的 cart 对象中，因此也不会反映在您的视图中。

Answer 2

尝试将$scope.userCart = UserCart.cart;更改为：

$scope.userCart= function() {
return UserCart.cart;
};