knockout.js - Table not updated when ko.observablearray changes -

i'm binding ko.observablearray table. each object (called 'group') in array bound table. each group holds (non-knockout) array of codes. each code bound row. each code has boolean, bound checkbox.

if none of booleans true in group, want checkboxes group enabled. if @ least 1 of booleans true in group, want false checkboxes group disabled, , true checkboxes enabled. when page loaded, works expected; however, when check or uncheck box, enabled/disabled status of boxes not change. looking @ debugger, observablearray being updated, data in table not.

page:

<table data-bind="foreach: {data: groups}">     <thead>         <tr>             <th colspan="3" data-bind="text: groupname"></th>         </tr>     </thead>     <tbody data-bind="foreach: {data: codes}">         <tr>             <td data-bind="text: codeid"></td>             <td data-bind="text: desc"></td>             <td>                 <input type="checkbox" data-bind="checked: prime, disable: $root.hasprime($parent) && !prime" />             </td>         </tr>     </tbody> </table> 

javascript function tests if there true values in group:

var hasprime = function (gr) {     (var = 0; < gr.codes.length; i++) {         if (gr.codes[i].prime === true) {             return true;         }     }     return false; }; 

fiddle: http://jsfiddle.net/nslpu/2/

if want two-way binding you'll need make things observable. in case, prime properties have observables:

var code1 = {     'codeid': 123,         'desc': 'code 1',         'prime': ko.observable(false) // <---- changed! }; 

this require corresponding changes in rest of code:

• plain js calls have invoke prime method current value
• bindings "do stuff" (like negation, on input) need invoke observable value negated

see this fiddle update.