Skip to main content

Using Model-View ViewModel design pattern in Kendo UI

Kendo UI is completely new to me and I got introduced to it when Brandon Satrom left Microsoft and joined the Kendo UI team. I had interacted with him when I was working on jQuery ‘Pinify’ plugin. Kendo UI is a HTML5, jQuery based framework for building both web and mobile applications. It not only provides a set of UI widgets and other data visualization components but also a framework for data binding, animation and drag-and-drop. Whilst I was looking into the framework I stumbled upon the Mode-View ViewModel (MVVM) design pattern built into it.

This design pattern (MVVM) helps you separate the Model (data) from the View. The ViewModel part of MVVM exposes the data objects which is consumed by the view and if the user changes the data in the view, the model will be updated with the new data.

In the above code, I'm creating a viewModel object that defines the data which will be consumed by the view. The View-Model object is created by calling the function kendo.observable, passing a JavaScript object. Here the keys firstname and lastname contain string data and fullname refers to a function which returns fullname by concatenating firstname and lastname.

Here’s the HTML form that would consume the data defined in the ViewModel:
This is a simple HTML form, but one thing to note here is the use of data-bind attributes. The data-bind attribute specifies the key to which it will be bound to in the ViewModel. Now that the View and the ViewModel are defined, they can be bound by calling the method kendo.bind($('form#testView'),viewModel).

When the page is loaded you'll be able to see values from the ViewModel being shown in the form fields. Now when a user changes the values it will be updated in the ViewModel i.e. when you change the firstname and lastname values it will be updated in the viewModel object and the fullname will be assigned the new value.

Comments

Popular posts from this blog

Custom validation messages for HTML5 Input elements using the constraint validation API

HTML5 has introduced several input types such as EMAIL, URL, RANGE, SEARCH, DATE, TIME, etc,. Most of the modern browsers have implemented them and are ready to be used in a HTML document. Another exciting feature introduced in HTML5 is the form validation. Instead of writing JavaScript to validate users input, browsers can now validate it and show an appropriate message if the validation fails. The validation message is shown in line with the field for which the validation has failed. The default error message is shown when the validation fails. In this post I'll explain how these error messages can be changed.

De-obfuscating javascript code in Chrome Developer Tools

I had blogged about JavaScript debugging with Chrome Developer Tools some time back, wherein I have explained how these developer tools can help in debugging javascript code. Today Google Chrome 12 was released and my Chrome browser was updated to this version. As with every release, there have been some improvements made on performance, usability etc,. One feature that stood out for me is the ability to De-obfuscate the javascript code.

What is Minification?

Minification is the process of removing unnecessary characters such as white spaces, comments, new lines from the source code. These otherwise would be added to make the code more readable. Minifying the source code helps in reducing the file size and thereby reducing the time taken to download the file. This is the reason why most of the popular javascript libraries such as jQuery are minified. A minified jQuery file is of 31 KB in size where as an uncompressed one is about 229 KB. Unfortunately, debugging minified javascript file…

Adding beforeRender and afterRender functions to a Backbone View

I was working on a Backbone application that updated the DOM when a response was received from the server. In a Backbone View, the initialize method would perform some operations and then call the render method to update the view. This worked fine, however there was scenario where in I wanted to perform some tasks before and after rendering the view. This can be considered as firing an event before and after the function had completed its execution. I found a very simple way to do this with Underscore's wrap method.