Knockout 3.2 component data context

Question

I am using Knockout 3.2 and the new component system. I am trying to have components that include sub-components.

Home Page (component - with HomePageViewModel) NewsFeed1 (component with HomePageViewModel.NewsFeedViewModel1) NewsFeed2 (component with HomePageViewModel.NewsFeedViewModel2)

HomePageViewModel

var viewModel = (function () {
    function viewModel() {
        this.message = ko.observable("Welcome to DKT!");
        this.newsFeedViewModel = new gr.viewModel();
        this.newsFeedViewModel2 = new gr.viewModel();
        this.newsFeedViewModel.message("Message 1");
        this.newsFeedViewModel2.message("Message 2");
    }
    return viewModel;
})();

NewsFeedViewModel

var viewModel = (function () {
    function viewModel() {
        this.message = ko.observable("This is the profile!");
    }
    return viewModel;
})();

As you can see the HomePageViewModel contains both the NewsFeedViewModel. I now want to be able to use these as the DataContext/BindingContext of my two components but this does not seem to work.

Home.html

<news-feed data-bind="newsFeedViewModel"></news-feed>
<news-feed data-bind="newsFeedViewModel2"></news-feed>

Both these components do not use the ViewModels from the HomePageViewModel but uses a new NewsFeedViewModel. How can I make the datacontext of both these components bind to the viewModels stored in the top component (home)?

Answer 1

Generally, you would want to supply your component with any data via params. For example, with your structure, you could create the component like:

ko.components.register("news-feed", {
    viewModel: function (params) {
       this.vm = params.vm;
    },

    template: "<h2>News Feed</h2><div data-bind=\"text: vm.message\"></div>"
});

Then, you would define the elements like:

<news-feed params="vm: newsFeedViewModel"></news-feed>

<news-feed params="vm: newsFeedViewModel2"></news-feed>

You could choose to pass the message in directly for each and/or choose whatever names make sense for your params (rather than vm).

Sample: http://jsfiddle.net/rniemeyer/fssXE/