Understanding AJAX Helpers in ASP.NET MVC

Shailendra Chauhan

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16 Aug 2022

Intermediate

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AJAX Helpers are used to create AJAX enabled elements like as Ajax enabled forms and links which performs request asynchronously. AJAX Helpers are extension methods of AJAXHelper class which exist in System.Web.Mvc namespace.

AJAX HTML

Element Example

AJAX-enabled link based on action/controller

@Ajax.ActionLink("Load Products", "GetProducts", new AjaxOptions {UpdateTargetId = "Products-container", HttpMethod = "GET" }) Output: <a data-ajax="true" data-ajax-method="GET" data-ajax-mode="replace" data-ajax-update="#Products-container" href="/Home/GetProducts">Load Products</a>

Unobtrusive AJAX

ASP.NET MVC supports unobtrusive Ajax which is based on jQuery. The unobtrusive Ajax means that you use helper methods to define your Ajax features, rather than adding blocks of code throughout your views.

Various configuration options for AJAX Helpers

The AjaxOptions class defines properties that allow you to specify callbacks for different stages in the AJAX request life cycle. There are following properties provided by AjaxOptions class for AJAX helpers:

Property

Description

Url

Specify the URL that will be requested from the server.

Confirm

Specify a message that will be displayed in a confirm dialog to the end user. When user clicks on OK button in the confirmation dialog, the Ajax call performs.

OnBegin

Specify a JavaScript function name which is called at the beginning of the Ajax request.

OnComplete

Specify a JavaScript function name which is called at the end of the Ajax request.

OnSuccess

Specify a JavaScript function name which is called when the Ajax request is successful.

OnFailure

Specify a JavaScript function name which is called if the Ajax request fails.

LoadingElementId

Specify progress message container’s Id to display a progress message or animation to the end user while an Ajax request is being made.

LoadingElementDuration

Specify a time duration in milliseconds that controls the duration of the progress message or animation.

UpdateTargetId

Specify the target container’s Id that will be populated with the HTML returned by the action method.

InsertionMode

Specify the way of populating the target container. The possible values are InsertAfter, InsertBefore and Replace (which is the default).

What is Cross Domain AJAX?

By default, web browsers allows AJAX calls only to your web application’s site of origin i.e. site hosted server. This restriction help us to prevent various security issues like cross site scripting (XSS) attacks. But, sometimes you need to interact with externally hosted API(s) like Twitter or Google. Hence to interact with these external API(s) or services your web application must support JSONP requests or Cross-Origin Resource Sharing (CORS). By default, ASP.NET MVC does not support JSONP or Cross-Origin Resource Sharing. For this you need to do a little bit of coding and configuration.

What do you think?

I hope you will enjoy the AJAX Helpers while programming with ASP.NET MVC. I would like to have feedback from my blog readers. Your valuable feedback, question, or comments about this article are always welcome.