What is View State? How to Store and retrieve values from View State. How to Enable Disable View State

Introduction:

In my previous article I have explained about Delete browser cookie using C#.Net,Asp.Net. In this article I am going to explain about viewstate, how to store and retrieve values to and from viewstate and how to enable and disable viewstate.

Explanation:

A Web application is stateless. A new instance of the Web page class is created every time that the page is requested from the server. This would ordinarily mean that all information in the page and in its controls would be lost with each round trip. For example, by default if a user enters information into a text box on an HTML Web page, that information is sent to the server. However, it is not returned to the browser in the response. 

To overcome this intrinsic limitation of Web programming, the ASP.NET page framework includes several state-management features to preserve page and control values between round trips to the Web server. One of these features is view state.

By default, the ASP.NET page framework uses view state to preserve page and control values between round trips. When the HTML for the page is rendered, the current state of the page and values that must be retained during postback are serialized into base64-encoded strings. They are then put into a hidden field or fields in the page.

You can access view state in your code by using the page's ViewState property. The ViewState property is a dictionary that contains key/value pairs that contain the view state data.

To disable view state for a control by default so that it can be enabled for child controls, set the ViewStateMode property of the control to Disabled. To disable view state by default for an entire page, set the ViewStateMode attribute of the @ Page directive to Disabled.

To disable view state for a control and its children so that it cannot be enabled for child controls, set the EnableViewState property of the control to false. To disable view state for an entire page and all of its child controls, set the EnableViewState attribute of the @ Page directive to false.

Data Types You Can Store in View State

You can store objects of the following types in view state:

·         Strings

·         Integers

·         Boolean values

·         Array objects

·         ArrayList objects

·         Hash tables

To add the values to viewstate

ViewState.Add("testvar", "asdasd");

To get the values from the viewstate

string viewStateValue = "";

if (ViewState["testvar"] != null)

    viewStateValue = ViewState["testvar"].ToString();

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