Using a computed column with JSON - json

Question

I am trying to make a computed column on data returned via JSON. I cannot get it to work. I either get a NAN value or it says the column does not exist.
javascript:
function commissionsViewModel() {
var self = this;
self.commissions = ko.observableArray();
ko.applyBindings(self, $("#commissions").get(0));
function LoadcommissionsFromServer() {
$.post(
'/commissions/data',
function (data) {
var results = ko.observableArray();
ko.mapping.fromJS(data, {}, results);
for (var i = 0; i < results().length; i++) {
self.commissions.push(results()[i]);
};
},
'json'
)
}
LoadcommissionsFromServer();
self.ComissionAmount = ko.computed(
function () {
return this.CommissionableAmount * this.Rate * this.Modifier;
});
return self;
}
var viewModel = commissionsViewModel();
What I am trying to accomplish is for it to recalculate the CommissionAmount after I change the modifier or rate.
EDIT
If I manually map the fields I get the NaN
function Commission(data) {
this.Status = ko.observable(data.Status);
this.OriginalCommissionCode = ko.observable(data.OriginalCommissionCode);
this.NewCommissionCode = ko.observable(data.NewCommissionCode);
this.InvoiceNumber = ko.observable(data.InvoiceNumber);
this.CustomerID = ko.observable(data.CustomerID);
this.CommissionableAmount = ko.observable(data.CommissionableAmount);
this.Modifier = ko.observable(data.Modifier);
this.Rate = ko.observable(data.Rate);
this.SalesAmount = ko.observable(data.SalesAmount);
this.NonSalesAmount = ko.observable(data.NonSalesAmount);
this.CommissionAmount = ko.computed(function () {
return this.CommissionableAmount * this.Rate * this.Modifier;
});
}
function commissionsViewModel() {
var self = this;
self.commissions = ko.observableArray();
$.post(
'/commissions/data',
function (allData) {
var mappedTasks = $.map(allData, function (item) { return new Commission(item) });
self.commissions(mappedTasks);
},
'json'
);
}
ko.applyBindings(new commissionsViewModel());

Answer 1

I assume Rate and Modifier are observables (You didn't provide their declaration) so you need to use the this.Rate() and this.Modififer() notations. They are functions, not properties.