Question

I get error of “Unable to parse Binding, ReferenceError: ‘calculateTotalPrice’ is undefined;
Bindings value: click: calculateTotalPrice

below is my simple code snippet

<div style="background-color:black; color:white; overflow:scroll; height:350px;width:300px" id="pricesku">
<span id="total" data-bind="text: totalCost"></span> 
<ul data-bind="foreach: price_quantity" style="list-style-type:none;">
<li>                  
<button data-bind="click: calculateTotalPrice(price)">CLICK THIS TO UPDATE TOTAL</button>                   
</li>             
</ul>
</div>

But when I do, click and provide function name, get an error above.

This is my View Modal

function ViewPriceObjectOnWeb(d) {

this.price_quantity = ko.observableArray(d);
this.totalCost = ko.observable(100);
this.calculateTotalPrice = function (p) {
var tp = this.totalCost() + p;
//$('#total').text(tp);
}

}

and on document ready i make AJAX Call that brings Data from server (this works fine) as below

$(document).ready(function () {   
var sku = "abcd";
$.ajax({
    url: "/api/values?clientSKU=" + sku, //this would give SKU/Price collection as JSON Serialized object from .NET/Server Side
    dataType: "json",
    asyc: false,
    type: "get",
    success: function (msg) {
    var skuandprice = $.parseJSON(msg);          
    ko.applyBindings(new ViewPriceObjectOnWeb(skuandprice), document.getElementById('pricesku'));
    },
    error: function (jqXHR, textStatus, errorThrown) {
    alert(textStatus + '  ' + errorThrown);
    }
    });
});

Can anyone help me what I am doing wrong here(i bet i am)? Thx in advance.

Answer 1

When you are inside a foreach loop, Knockout expects any functions or properties in the data-bind to be defined within the entries of the array, which in this case are the values in price_quantity. To access functions and properties that are defined in the object that holds the array, you use the $parent identifier. So to use calculateTotalPrice inside your loop, you need to do:

<li>                  
    <button data-bind="click: $parent.calculateTotalPrice">CLICK THIS TO UPDATE TOTAL</button>                   
</li>

The view model:

function ViewPriceObjectOnWeb(d) {
    var self = this;
    self.price_quantity = ko.observableArray(d);
    self.totalCost = ko.observable(100);
    self.calculateTotalPrice = function (p) {
        var tp = self.totalCost() + p;
        self.totalCost(tp);
    };
}

Working example (using hard-coded prices): http://jsfiddle.net/jonhopkins/fn7vc/2/