How to update Knockout.js view model with server

Question

I have Knockout.js view model that has nested observable arrays.

 function ParentVM(data) { var self = this; self.childs= ko.observableArray([]); ko.mapping.fromJS(data, mapping, this); } function ChildVM(data) { var self = this; self.propertyA = ko.observableArray([]); self.propertyB = ko.observable(); ko.mapping.fromJS(data, mapping, this); } function GrandChildVM(data) { var self = this; self.propertyX = ko.observable(); self.propertyY = ko.observable(); self.propertyZ = ko.observable(); ko.mapping.fromJS(data, mapping, this); }

I have following bindings:

 data-bind="value: propertyX, valueUpdate: 'keydown'"

Now, how can I add event handler to call my REST endpoint to update view model state when these properties changes?

Steen Tøttrup · Accepted Answer · 2012-07-27 10:48:12Z

1

If I understand you correctly, this is what you can do:

function ChildVM(data) { var self = this; self.propertyA = ko.observableArray([]); self.propertyB = ko.observable(); ko.mapping.fromJS(data, mapping, this); self.propertyA.subscribe(function (newValue) { /* call you're api with new value! */ }); self.propertyB.subscribe(function (newValue) { /* call you're api with new value! */ }); }

answered Jul 27, 2012 at 10:48

Steen Tøttrup

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4 Comments

Fdr Over a year ago

Yes, but this does not seem to work. The subscribed callback does not get called.

Steen Tøttrup Over a year ago

That doesn't make any sense, is the model bound correctly? Do any values in the parameters get shown in the UI?

Fdr Over a year ago

Thanks, the problem was that when the data was initialized it did not use the provided mapping. Changing ko.mapping.fromJS(data) to ko.mapping.from(data, mapping) fixed the issue and subscribing to properties works.

Steen Tøttrup Over a year ago

Please make sure to mark me answer as the correct one, if it solved your problem. :)

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