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Can observed knockouts be tied to a switch value?

Is it possible to bind a knockout observable property to a radio button using value binding?

Here's what I'm trying to do, but the value ends up being the string "Object Object" instead of the actual instance of my observable property:

<input type="radio" name="vehicleGroup" data-bind="checked: vehicleGroupViewModel().selectedGroupOption , value:vehicleGroupViewModel().car" />

<input type="radio" name="vehicleGroup" data-bind="checked: vehicleGroupViewModel().selectedGroupOption , value:vehicleGroupViewModel().truck" />

Here's the view models I'm using:

var VehicleGroupViewModel = function(){
    var self = this;
    this.selectedVehicleGroup = ko.observable();
    this.selectedGroupOption = ko.observable();
    this.selectedGroupOption.subscribe(function (newVal) {
        self.selectedVehicleGroup(newVal);
    }
    this.selectedGroup = ko.observable();
    this.car = ko.observable(new VehicleViewModel());
    this.truck = ko.observable(new VehicleViewModel());
}

var VehicleViewModel = function(){
    this.name = ko.observable();
}

So in the end, I would like the vehicle or Truck VehicleViewModel to be in the selected observable vehicle group.

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3 answers


As described here only Nodes have the ability to bind an arbitrary JavaScript object to a value. Other inputs require a string value, so your value returns "[Object Object]".

You can still do what you want, but you have to manually match the key and find the appropriate object yourself. Here is a fiddle that demonstrates:



http://jsfiddle.net/jearles/JcPXy/

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FYI for other readers who have come to the accepted answer, KO v3 added the checkedValue binding which now makes this possible.



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I need it too. My solution was similar to John Earles, except it was subscribe

used instead computed

: 
self.selectedVehicleGroup = ko.computed(function(){
    return ko.utils.arrayFirst(self.availableGroups(), function (group) { return group.name() == self.selectedGroupOption(); });
});

http://jsfiddle.net/JcPXy/91/

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