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Detect Browser Refresh to avoid events fired again in ASP.NET

Apr 6, 2010

If you have created an aspx page using C# and ASP.NET and have put a button on it. And in the Click event of this button if you are inserting some data in database , after click if user refresh the page than click event gets fired again resulting data insertion to database again, to stop events on the page getting fired on browser refresh we need to write bit of code to avoid it.

In this example I’ve put a Label and a Button on the page, on click the label Text becomes Hello and when I refresh the page label's text again becomes Hello

Markup


<%@ Page Language="C#" AutoEventWireup="true"CodeFile="Default.aspx.cs" Inherits="_Default" %>
<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form2" runat="server">
<div>
<asp:Label ID="Label1" runat="server" Text="Label">asp:Label><br />
<br />
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />div>
</form>
</body>
</html> 

Now in the Page_Load event I m creating a Session Variable and assigning System date and time to it , and in Page_Prerender event I am creating a Viewstate variable and assigning Session variable's value to it than in button's click event I am checking the values of Session variable and Viewstate variable if they both are equal than page is not refreshed otherwise it has been refreshed 

 
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
Session["CheckRefresh"] =
Server.UrlDecode(System.DateTime.Now.ToString());
}
}
protected void imgbtn_Click(object sender, ImageClickEventArgs e)
{
//Label2.Text = imgbtn.ToolTip;
}
protected void Button1_Click(object sender, EventArgs e)
{
if (Session["CheckRefresh"].ToString() == ViewState["CheckRefresh"].ToString())
{
Label1.Text = "Hello";
Session["CheckRefresh"] =
Server.UrlDecode(System.DateTime.Now.ToString());
}
else
{
Label1.Text = "Page Refreshed";
}
}
protected void Page_PreRender(object sender, EventArgs e)
{
ViewState["CheckRefresh"] = Session["CheckRefresh"];
}
}

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11 comments :

test said...

Super...Great Work!!!

Anto Reegan said...

i want redirect when page get refreshing what should i do...but i also try responce.redirect mehod but it wont work..plz help me..

krishna g said...
This comment has been removed by the author.
Anonymous said...

i got this error for session object...plz help

Object reference not set to an instance of an object.

thanks in adv

Anonymous said...

Thanks! It worked for me, but in my case, i've used Vb.net.

Anonymous said...

Thanks for this simple and elegant solution!

Nams said...

Great work!!! Is this really coded by you or you have taken it from codeproject's article which is written by Namita Patil? :)))

Akhilesh Chintu said...

Good one..!!

Pandiyan M said...

Thank you Suresh Bro,

Pandiyan M said...

No words to say but Am Happy

adi r said...

thanks it's work for me.

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