I am learning knockout js and have begun building a simple shopping cart.
This shopping cart basically ask the user to select a category from a dropdownlist and then a second dropdownlist is then populated with products.
When the user selected a product, the product information is displayed i.e. name/price/qty/total. An 'add Item' button is also visible.
the qty data is a textbook where the user can increment the value. If the user increments the qty value the total value will calculate the new total i.e. (price * qty).
When the user clicks the add item button the product id, name, qty and total are stored and displayed (except id) in an adjacent div i.e. cart list.
The problem i am having is that when an item is in the shopping cart with qty 1 and i want to add a new item to the cart with a qty of 2. The qty value in the cart is also changing to 2. The values should stay at 1 also the total value in the shopping cart is matching that of the new item.
here is the code:
<div id="exp2">
<div>
<span>
<select id="ddlCat" data-bind="options: lstCategories, optionsText: 'name',
optionsValue: 'id', optionsCaption: 'Select Category...',
value: selectedCate"></select>
</span>
<span data-bind="visible: lstProducts().length > 0">
<select id="ddlProd" data-bind="options: lstProducts, optionsText: 'name',
optionsValue: 'id', optionsCaption: 'Select Product...',
value: selectedProdId"></select>
</span>
<span data-bind="with: selectedProd()">
Price: £<span id="pPrice" data-bind="text: price"></span>,
Qty <input type="text" id="pQty" data-bind="value: quantity" style="width:30px;"
placeholder="" required />
SubTotal: £<span data-bind="text: itemTotal()"></span>
<span><button id="btnAdd" class="btnAdd" data-bind="click: addItem">Add to cart</button></span>
</span>
</div>
<div>
<h3>Items In Cart</h3>
<ul id="lstCart" data-bind="foreach: cart">
<li>
Name: <span data-bind="text: name"></span>
Qty: <span data-bind="text: qty"></span>
Item Total: £<span data-bind="text: itemTotal"></span>
</li>
</ul>
Sub Total: £<span data-bind="text: subTotal()"></span>
</div>
</div>
Javascript
var categories = [];
var products = [];
var cartLines = [];
$.ajax({
url: '../KnockoutTut/page5GetCat',
type: "GET", cache: false, async: false,
contentType: "application/json; charset=utf-8",
dataType: "json", traditional: true,
success: function (data) {
//alert('Process Successful');
for (var i = 0; i < data.length; i++) {
var id = data[i].id; var name = data[i].name;
//var nCat = new Category(id, name);
categories.push( new Category(id,name));
}
},
error: function (jqXHR, textStatus, errorThrown) {
//alert("Error")
alert(jqXHR.status + "," + jqXHR.responseText + "," + errorThrown);
}
});
function getProd(catId) {
products = [];
var value = { 'value': catId };
var json = JSON.stringify(value);
$.ajax({
url: '../KnockoutTut/page5GetProd',
type: "POST", data: json, cache: false, async: false,
contentType: "application/json; charset=utf-8",
dataType: "json", traditional: true,
success: function (data) {
//alert('Process Successful');
for (var i = 0; i < data.length; i++) {
var id = data[i].id; var name = data[i].name;
var price = data[i].price; var qty = data[i].qty;
products.push(new Product(id, name, price, 1));
}
},
error: function (jqXHR, textStatus, errorThrown) {
//alert("Error")
alert(jqXHR.status + "," + jqXHR.responseText + "," + errorThrown);
}
});
}
function Category(id, name) {
this.id = id;
this.name = name;
};
function Item(id, name, qty, itemTotal) {
this.id = id;
this.name = name;
this.qty = qty;
this.itemTotal = itemTotal;
};
function Product(id, name, price, qty) {
this.id = id;
this.name = name;
this.price = price;
this.qty = qty;
};
function viewModel() {
var self = this;
self.lstCategories = ko.observableArray(categories);
self.lstProducts = ko.observableArray([]);
self.cart = ko.observableArray([]);
self.selectedCate = ko.observable();
self.selectedProdId = ko.observable();
self.selectedProd = ko.observable();
self.quantity = ko.observable(1);
self.catQty = ko.observable();
self.itemTotal = ko.pureComputed(function () {
return self.selectedProd() ? self.selectedProd().price * parseInt("0" + self.quantity(), 10) : 0;
});
self.subTotal = ko.pureComputed(function () {
var total = 0;
$.each(self.cart(), function () { total += this.itemTotal() })
return total;
});
self.selectedCate.subscribe(function (pCatId) {
var catId = pCatId;
if ($.isNumeric(catId)) {
getProd(catId);
}
self.lstProducts(products);
});
self.selectedProdId.subscribe(function (pProdId) {
var pId = pProdId;
var match = ko.utils.arrayFirst(lstProducts(), function (item) {
return pId === item.id;
});
self.selectedProd(match);
//alert(selectedProd().qty);
});
self.addItem = function (item) {
var nId = item.id; var nName = item.name; var cartQty = quantity; var iTot = itemTotal;
cart.push(new Item(nId, nName, cartQty, iTot));
//cart.push(cartLines);
};
};
ko.applyBindings(viewModel, document.getElementById("exp2"));
Remember i am new to knockout js. so please excuse the bad coding. Thanks
