Call nav functions from a sub Knockout ViewModel

Question

I'm Building a Single Page Application using ASP.NET MVC, Knockout, nav.js...etc.,

Two View Model:

1. FatherViewModel;
2. SonViewModel;

FatherViewModel has All the Navigation methods, FatherViewModel has an instance of SonViewModel,

Q: How to access those Navigation methods from the SonViewModel?

FatherViewModel = function () {
    var self = this;
    var dataSource = {...}

    self.sonViewModel = new SonViewModel();

    self.nav = new NavHistory({
        params: {...},
        onNavigate: function (navEntry) {...}
    }).initialize({ linkToUrl: true });
    //navigation methods:
    self.gotoHomePage = function (){...}
}
SonViewModel = function () {
    var self = this;
    var dataSource = {...}

    //...
}

Answer 1

In order to access the father's methods from the son viewmodel, you need to pass a reference of the father to the son, like so:

FatherViewModel = function () {
    var self = this;
    var dataSource = {...}

    self.sonViewModel = new SonViewModel(self);

    self.nav = new NavHistory({
        params: {...},
        onNavigate: function (navEntry) {...}
    }).initialize({ linkToUrl: true });
    //navigation methods:
    self.gotoHomePage = function (){...}
}
SonViewModel = function (father) {
    var self = this;
    self.father = father;
    var dataSource = {...}

    function gotoHomePage() {
        self.father.gotoHomePage();
    }

    //...
}