CODEWITHSUNDEEP
knockout.jsknockout-mapping-plugin
renathy
renathy

Reputation: 5355

knockout adding new properties to already existing view model

There is a knockout model:

var customMapping = {
    update: function (options) {
        var result = ko.mapping.fromJS(options.data);
            var self = this;
            self.computeTest = ko.computed(function () {
                return "Test" + self.newObs();
            });

        return result;
    }
};

var model = function() 
{
   var self = this;
   self.Test = ko.observable();

   self.init = function() {
       // create ajax call
       // in success do mapping
       ko.mapping.fromJS(data, customMapping, self); //this mapping should update existing model - adding new observables and computed
   }

   ko.applyBindings(self, $("#id")[0]);
}

var m = new model();
m.init();

So: 1) I have knockout model. Within it some functions are defined and also a list of observables.

2) Knocokut binding is called before data came from server.

3) Model data are loaded using m.init().

This should call custom mapping and create new observables (based on data from server), as well as some computed variables. However, this custom binding doesn't work. It doesn't create any new observables. I believe that this should be 'update' mapping, but I do not understand how can I extend inside it existing model

Upvotes: 0

Views: 391

Answers (1)

Jeroen
Jeroen

Reputation: 63719

Given your code there's actually perhaps a shortcut available: move the ko.applyBindings call to the init method, right below the mapping call.

Failing that you'll need to use a placeholder / empty / fake Ajax result to wire up a "default" view model.

Upvotes: 1

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