KnockoutJS checked binding issue

Question

I am relatively new to knockoutjs, but I seem to be having a problem with an observableArray of checkboxes, the checkboxes have some observable properties for checked, and disabled.

Using knockout I can check and uncheck the box, but it seems that once I interact with the checkbox manually (IE by clicking it with the mouse) the underlying data seems to be changing but I can't use knockout to check or uncheck the box anymore.

HTML

<div id="filterByPrice" data-bind="foreach: priceFilters">
    <div>
        <input type="checkbox" data-bind="attr: {id: $index, value: value, checked: checked, disable: disabled}" />
        <span data-bind="text: label"></span>
    </div>
</div>

Javascript

function FilterBy(name, value, label) {
    this.name = name;
    this.value = value;
    this.label = label;
    this.disabled = ko.observable(false);
    this.checked = ko.observable(false);
}

$(function () {
    var viewModel = {
        priceFilters: ko.observableArray([
        new FilterBy("price0", "0", "All Prices")])
    };

    ko.applyBindings(viewModel);
});

http://jsfiddle.net/paulwilliams0/EYEz2/

Is there something that I am doing that is wrong? Not only am I new to knockout, but I am new to MVVM in general. Thanks a lot

chris vietor chris vietor · Accepted Answer · 2013-05-08T16:01:01

here i have a working version of your example:

http://jsfiddle.net/infantrash/hVac2/2/

data-bind attribute for your checkbox: use the build-in binding handlers, attr: { id: $index } is ok, but value, checked and disable are should not be in the curly brackets.

use knockout functions for your functionality instead of mixing jQuery into it.

function viewModel(){
var self = this;
self.priceFilters = ko.observableArray([
    new FilterBy("price0", "0", "All Prices"),
    new FilterBy("price1", "1", "1st Price")
]);


self.checkAllPrices = function(){
    ko.utils.arrayForEach(self.priceFilters(), function(item){
        item.checked(true);
    })
};
self.unCheckAllPrices = function(){
    ko.utils.arrayForEach(self.priceFilters(), function(item){
        item.checked(false);
    })
};

}

i changed the viewModel to a function instead of using the object literal notation, but that's just my preferred way, you can use the object literal notation if you want.

KnockoutJS checked binding issue

1 Answers