Knockout + Bootstrap 3 Radio Buttons

Question

Related to: Bootstrap Radio Button Group

HTML:

<div class="btn-group" data-toggle="buttons">     <label class="btn btn-primary">         <input type="radio" name="options" id="option1" value="1" data-bind="checked: optionsValue"> Option 1     </label>     <label class="btn btn-primary">         <input type="radio" name="options" id="option2" value="2" data-bind="checked: optionsValue"> Option 2     </label>     <label class="btn btn-primary">         <input type="radio" name="options" id="option3" value="3" data-bind="checked: optionsValue"> Option 3     </label> </div> <br /> <span data-bind="text: optionsValue"></span> 

Javascript:

var ViewModel = function() {     this.optionsValue = ko.observable() };  ko.applyBindings(new ViewModel()); 

JsFiddle:

• Without data-toggle: http://jsfiddle.net/fDMM2/
• With data-toggle: http://jsfiddle.net/Kf3tj/1/

---

I have the above code which I'm trying to get working as I expect it to. The problem is that when data-toggle="buttons" is added to the btn-group div (as in the Bootstrap 3 example) the knockout binding stops working. If I leave the data-toggle off of the buttons group then the binding works as expected but the button group looks awful. I know that this didn't work in Bootstrap 2 because they didn't actually use the radio input for their radio styling. How come it refuses to work now even though they do?

Answer 1

The bootstrap buttons and the knockout checked binding are still not playing nice:

• knockout uses the click event inside the checked binding to tigger the underlaying observable to change
• bootstrap subscribes on the click event to do the toggling but calls e.preventDefault() so KO won't be notified about the click.

One possible solution is to create a custom binding handler where you subscribe on the change event (this is fired by bootstrap on toogle) and set your observables value there:

ko.bindingHandlers.bsChecked = {     init: function (element, valueAccessor, allBindingsAccessor,     viewModel, bindingContext) {         var value = valueAccessor();         var newValueAccessor = function () {             return {                 change: function () {                     value(element.value);                 }             }         };         ko.bindingHandlers.event.init(element, newValueAccessor,         allBindingsAccessor, viewModel, bindingContext);     },     update: function (element, valueAccessor, allBindingsAccessor,     viewModel, bindingContext) {         if ($(element).val() == ko.unwrap(valueAccessor())) {              setTimeout(function () {                 $(element).closest('.btn').button('toggle');              }, 1);          }     } } 

And use it in your view with:

<label class="btn btn-primary">     <input type="radio" name="options" id="option1" value="1"             data-bind="bsChecked: optionsValue"> Option 1 </label> 

Original demo using Bootstrap 3.0.2 JSFiddle.
Updated demo using Bootstrap 3.2.0 JSFiddle.