I'm trying to figure out what I'm misunderstanding with Knockout's mapping library. I've stripped it down to a simple example, and still can get it to fail (rather, not update with the mapped variables) with the fromJS
call.
What am I getting fundamentally wrong in this example?
// Here's my view model
var ViewModel = function() {
this.firstName = ko.observable('first');
this.lastName = ko.observable('last');
};
var myVM = new ViewModel();
ko.applyBindings(myVM); // Apply to Knockout (works)
myVM.lastName('maiden name'); // Test an update (works)
var newData = {firstName: 'new', lastName: 'person'};
// Try update the ViewModel
ko.mapping.fromJS(newData, myVM); //(No update, or error)
// Intended result - UI updates to 'new person'
And the corresponding view:
<div class='liveExample' >
<p>First name: <input data-bind='value: firstName' /></p>
<p>Last name: <input data-bind='value: lastName' /></p>
</div>
The ko.mapping.fromJS
handles the parameters a little bit tricky (see my answer here), so the second parameter is normally the mapping options:
ko.mapping.fromJS(newData, {} /* mapping options */, myVM);
Demo JSFiddle.