Hi friends, in this article I will explain about ASP.NET ViewState example in VB.NET or C# || How to use ViewState ASP.NET || Working with ViewState in ASP.NET.
- ViewState is the mechanism that allows state values to be preserved across page postbacks.
- I already explained about state management using cookies and sessions.
- Viewstate is also the mechanism used to store the values across the page postbacks.
- Maintaining the viewstate is the default for ASP.NET web pages.
- If you don’t want to maintain the ViewState then include the directive <%@ Page EnableViewState="false" %> at the top of an .aspx page or add the attribute EnableViewState="false" to any control.
I will explain the viewstate with small example.
Take the below controls in your .aspx page.
In ASP.NET:
|
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>ASP.NET
ViewState example: how to use ViewState in asp.net</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h2 style="color:Navy">ASP.NET ViewState
example</h2>
<asp:Label
ID="Label1"
runat="server"
ForeColor="DarkGreen"
Font-Size="Large"
>
</asp:Label><br />
<asp:Button
ID="Button1"
runat="server"
OnClick="Button1_Click"
ForeColor="Red"
Font-Bold="true"
Text="Show Button Click Status"
/> <br/>
<asp:Label ID="Label2" runat="server" Text="Label"></asp:Label></div>
</form>
</body>
</html>
|
After that write the following code in button click and page
load.
In VB.NET:
|
Imports System
Partial Class viewstate
Inherits
System.Web.UI.Page
Protected
Sub Button1_Click(ByVal
sender As Object,
ByVal e As
System.EventArgs) Handles Button1.Click
Dim
clickCounter As Integer
If
ViewState("ClickCounter") Is Nothing Then
clickCounter = 1
Else
clickCounter = CInt(ViewState("ClickCounter"))
+ 1
End If
ViewState("ClickCounter")
= clickCounter
Label1.Text = "Button clicked " & clickCounter & " times."
End Sub
Protected
Sub Page_Load(ByVal
sender As Object,
ByVal e As
System.EventArgs) Handles Me.Load
If (Not IsPostBack) Then
Label2.Text = "First Time"
Else
Label2.Text = "After Postback"
End If
End Sub
End Class
|
In C#:
|
using Microsoft.VisualBasic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
partial class viewstate :
System.Web.UI.Page
{
protected
void Button1_Click(object sender,
System.EventArgs e)
{
int clickCounter = 0;
if
(ViewState["ClickCounter"] ==
null) {
clickCounter = 1;
} else
{
clickCounter =
Convert.ToInt32(ViewState["ClickCounter"])
+ 1;
}
ViewState["ClickCounter"]
= clickCounter;
Label1.Text = "Button clicked " + clickCounter + " times.";
}
protected
void Page_Load(object sender,
System.EventArgs e)
{
if
((!IsPostBack)) {
Label2.Text = "First Time";
} else
{
Label2.Text = "After Postback";
}
}
Public
viewstate()
{
Load += Page_Load;
}
}
|
Viewstate is stores that even postback. The above shows how
data stored while postbacks.When you run the page first time (means it’s not
postback) label2 shows First Time. When you click on the button it will be
postbacked and label2 shows After Postback and
count will be decreased.
The output is as follows.
When you run the page postback
After clicking the button
No comments:
Post a Comment