07 May 2012

Customer KnockoutJS and MVC demo using JSON

After reading about KnockoutJS I have decided to create a simple demo using JSON to comunicate with the web server.
The application retrieves a Customer from an ASP.Net MVC Action and sends it to be saved.

The KnockoutJS is a JavaScript Model View ViewModel (MVVM) framework.
The View Model object contains properties which values are specified as ko.observable(). Knockout will automatically updates the UI when the view model changes.
KnockoutJS has a declarative binding syntax where the HTML view elements are bind with our view model object. Knockout uses the "data-bind" attribute in the HTML elements for the data binding.

To learn the basics goto the KnockoutJS site by pressing here

1) KnockoutJS
2) json2.js - for json parsing
4) jQuery

The Asp.Net MVC Controller have the actions to Get and Add a customer.

namespace KnockoutDemo.Controllers
    public class HomeController : Controller
        public ActionResult Index()
            ViewBag.Message = "";

            return View();

        public JsonResult Get(int customerID)
            // Get the customer ...
            Customer customer = new Customer {CustomerID = customerID, FirstName = "John", LastName = "Doe", IsMale = true };

            return Json(customer);

        public JsonResult Add(Customer customer)
            // Save the customer ...

            // return status message 
            var message = "Customer: " + customer.FirstName + " " + customer.LastName + " Added.";
            message += " IsMale: " + customer.IsMale.ToString();
            return Json(message);


The Asp.Net MVC model is the customer:
    public class Customer
        public int CustomerID { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public bool IsMale { get; set; }

The Asp.Net MVC Layout:
 <!DOCTYPE html>
    <meta charset="utf-8" />
    <link href="@Url.Content("~/Content/Site.css")" rel="stylesheet" type="text/css" />
    <script src="@Url.Content("~/Scripts/jquery-1.5.1.min.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/modernizr-1.7.min.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/knockout.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/json2.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/knockout.validation.js")" type="text/javascript"></script>
    <div class="page">
            <div id="title">
                <h1>Knockout Demo</h1>
        <section id="main">

And finally the Asp.Net MVC view has the KnockoutJS specifics:
    ViewBag.Title = "Add Customer";

<form action="" method="post">
<b>Customer Number: </b> <span data-bind="text: CustomerID"></span><br />
<br />
<b>First Name: </b><input data-bind="value: FirstName" style="width: 200px;" type="text" /> <br />
<br />
<b>Last Name: </b><input data-bind="value: LastName" style="width: 200px;" type="text" /> <br />
<br />
<input data-bind="checked: IsMale" type="checkbox" /><b>Male</b><br />
<br />
<input data-bind="click: KnockoutDemoNamespace.addCustomer" type="button" value="Add Customer" /><br />
<div id="message">

The KnockoutJS has the following specifics:
1) View Model object: customerViewModel
2) HTML View: The HTML from the page with the KnockoutJS specific attributes for data binding
The demo performs a data bind with a span, and the input types text, checkbox and button.
Note that the "data-bind" has the html element attribute to be affected and the View Model property associated.
3) View Model activation: ko.applyBindings(viewModel);

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