dropdown knockoutjs with value from server

Question

I am working on a drop down menu within a TR .. I have true, false or none as the value that I receive from server and I want that to change the drop down option as in example below.

The first one is working but I want the second one to function as the first one

Example is here: http://jsfiddle.net/3xLgJ/

This is my HTML:

       <div data-bind='text: incomingValue'></div>

       <select data-bind="value: incomingValue">
             <option value="true">Yes</option>
             <option value="false">No</option>
             <option value="none">Don't Know</option>
      </select>

How can I implment this as above as this is within a tr and to function as above

      <select  data-bind='options: yesno, value: incomingValue'/>

Here is my knockout

    var myModelView = function () {
    self = this;
    self.yesno = ko.observableArray(['Yes', 'No', 'Don\'t know']);
    self.incomingValue = ko.observable('none');
    };

    var moView = new myModelView();

    ko.applyBindings(moView);  

Thanks

Thanks

Answer 1

The best solution is probably to slightly reconstruct the view model to use objects instead of simple strings:

// Create a "class" that represents an option
var Option = function(id, caption) {
    this.id = id;
    this.caption = caption;
};

Now you populate the observable array with objects constructed from this function:

self.yesno = ko.observableArray([
    new Option('true', 'Yes'),
    new Option('false', 'No'),
    new Option('none', 'Don\'t know')
]);

You can use the "optionsText" binding to correctly bind these objects to the markup:

<select data-bind="options: yesno,
                   optionsText: 'caption',
                   value: selectedItem"></select>

If you receive a string "none" from the server, you need to find the object representing this option:

var incomingValue = 'none';

// Find the first object that is a match in the observable array "yesno"
var incomingItem = ko.utils.arrayFirst(self.yesno(), function(item) {
    return item.id == incomingValue;
});

self.selectedItem = ko.observable(incomingItem);

When displaying the selection somewhere else you'll need to consider that the selection is represented by an object:

<div data-bind='text: selectedItem().caption'></div>

Demo: http://jsfiddle.net/3xLgJ/2/