Auto postback in ASP.NET

Introduction

After updating this article on 06 July 2009, I see that there is someone who thinks that I don’t know that there are other solutions to this task today. As Stephen Inglish pointed out in a message, one of them is to use the AJAX timer module, and as fare as I know, there may be other solutions to.

Back in 2005, when I first wrote this article using Visual Studio 2003, I was not able to find a solution for automatic postback at a regular time schedule. After searching for a time, without finding anything, I wrote this JavaScript and shared it with the CodeProject community.

After the article was published in 2005, there have been some comments from isikiss and obed21, members of the community, which have improved the code. The reason why I’m updating this article, even though it is outdated, is that there are still people who read this article and I think they deserve an updated code.

Using the code

Start a new ASP.NET Web Application. Call it whatever you want, maybe TimerTest, and do the following:

In Design mode, click on the Source button and paste this JavaScript inside the head tag.

<script language="JavaScript" type="text/javascript">
<!--
// Script to generate an automatic postBack to the server
var secs
var timerID = null
var timerRunning = false
var delay = 1000
function InitializeTimer()
{
    // Set the length of the timer,
     // in seconds. Your choise
    secs = 5

    StopTheClock()
    StartTheTimer()
}
function StopTheClock()
{
    if(timerRunning)
        clearTimeout(timerID)
    timerRunning = false
}
function StartTheTimer()
{
    if (secs==0)
    {
        StopTheClock()

        //Generate a Postback to the server
        document.forms[0].submit()  
     
    }
    else
    {
        secs = secs - 1
        timerRunning = true
        timerID = self.setTimeout("StartTheTimer()", delay)
    }
}
//-->
</script>

Your Body have to look something like this. The most important thing is to add onload="InitializeTimer()" inside the <body> tag.

<body onload="InitializeTimer()">
<form id="form1" runat="server">
 <div>
       The time is:   <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</div>
</form>
</body>

In the code-behind, you can paste in this just to see something happening.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) _
          Handles Me.Load

  'This is just to se something happening
  Label1.Text = Now.ToString("hh:mm:ss")

  'Put the code to execute here.
End Sub

Leave it like this. The only thing it’s doing is that it posts back to the server, and in this example, it’s refreshing the time every 5 seconds.

And that’s all.

History

06 July 2009: The article was made when I was using Visual studio 2003. There have also been some comments by isikiss and obed21, members of the community, that have improved the code. I have implemented the improvements they have suggested and used Visual Studio 2008 to test it.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Sigurd Johansen

Web Developer

Norway

Member

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exactly what i needed

weirdlNet

23:57 26 Oct '09

This is a simple solution that works perfectly for me. I cannot add AJAX to my project, and I'm not good in javascript, so I didn't think of this. Thank you very much for this code
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My vote of 1

Rogic

1:10 21 Jul '09

complete crap
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Re: My vote of 1

Sigurd Johansen

6:30 21 Jul '09

Thank you for your gently comment.
Sign In·View Thread·Permalink	5.00/5 (1 vote)

Query

lovedotnet

19:02 20 Jul '09

Hi, nice logic, but i have a small query...I guess we can use meta tag for submitting the page..right? ex: <meta http-equiv="Refresh" content="30"> Please correct me, if i am wrong. thanks, pradeep.
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Re: Query

Sigurd Johansen

6:28 21 Jul '09

You can use the <meta http-equiv="refresh" content="30">, but it is a big difference between a refresh like this and a postback every 30 sec in an aspx page. A postback takes care of every value between postbacks, but a refresh doesn’t.
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My vote of 1

Kronass

1:13 14 Jul '09

This is a very very very basic concept that every person who works in javascript would know it
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Re: My vote of 1

Sigurd Johansen

10:36 18 Jul '09

Thank you for your comment, but what about those who are not so familiar with javascript as you are? If we all where experts we didn’t need the Codeproject community.
Sign In·View Thread·Permalink	1.00/5 (1 vote)

Yes .. really outdated

Abhishek Sur

21:21 13 Jul '09

Even google is using this in Gmail for long and now they are moving for some replacements. Anyway, even though outdated, Its really a good technique as most of the great sites use this. Abhishek Sur My Latest Articles Working with Excel using MDAC Basics on LINQ and Lambda Expressions Create .NET Templates
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[My vote of 2] Outdated

Stephen Inglish

13:19 7 Jul '09

There is no need to do JavaScript manually anymore to cause an ASP.NET postback. Utilize the Timer control in your page to force a postback in an interval. Set the Interval property of the Timer control to the number of milliseconds you want to wait.

Be sure the include the ScriptManager control first

<html xmlns="http://www.w3.org/1999/xhtml">
<head  runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1"  runat="server">
    <div>
        <asp:ScriptManager ID="ScriptManager1" runat="server"/>
        <asp:Timer ID="Timer1" runat="server" OnTick="Timer1_Tick" Interval="1000"/>
        <asp:Label ID="Label1" runat="server" Text="Label"/>
    </div>
    </form>
</body>
</html>

And in the Code behind...

        protected void Page_Load(object sender, EventArgs e)
        {
            // This is here to let you know the application does tick
            Label1.Text = DateTime.Now.ToString();
        }
 
        public void Timer1_Tick(object sender, EventArgs e)
        {
           // Do whatever you wanted to do just on the timer events
        }

Stephen Inglish
Consultant
Sogeti USA
MCPD: Windows Developer
MCPD: Web Developer
MCPD: Enterprise Developer

Re: [My vote of 2] Outdated

VaSig

21:58 7 Jul '09

The ScriptManager is an AJAX Control isn't it. I will assume that not everybody is using AJAX. Are those who are not using AJAX outdated after your opinion?
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Re: [My vote of 2] Outdated

Stephen Inglish

7:36 17 Jul '09

Yes, the ScriptManager / UpdatePanel are AJAX controls, however they are built into Visual Studio 2008 installations by default. The other AJAX extensions (textbox extender, expander, modal popup, etc...) are still a referenced .dll away.

Yes, I would say that if there is a globally available solution to designing a wheel (ASP.NET auto-postback), to redesign it again (Manual JavaScript), is outdated.

Stephen Inglish
Consultant
Sogeti USA
MCPD: Windows Developer
MCPD: Web Developer
MCPD: Enterprise Developer

Re: [My vote of 2] Outdated [modified]

Sigurd Johansen

8:44 17 Jul '09

Yes, I can agree that today it is outdated. This article was written in 2005, and at that time I was not able to find any solution to update a web site at a regular time scedule. The reason why I'm updating the article is that there are still people who read this article and they deserve to have an updated script. modified on Saturday, July 18, 2009 1:09 PM
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Re: [My vote of 2] Outdated

Md. Marufuzzaman

21:20 20 Jul '09

Hmmm Md. Marufuzzaman
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your article has helped me so much!

79167115

12:15 7 Jul '09

Thanks，your article has helped me so much!I am a software fan,I am very like your article,though I am chinese.my site the firejay welcome you.
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Not Posting back

Agweet

3:13 5 Aug '08

Hi All...i read the article and have made all the changes to cater for it in c# and to no success...my page doesnt post back automatically...can any1 help my code:

<script type="text/javascript" language="javascript">  

        // Script to generate an automatic postBack to the server

        var secs

        var timerID = null

        var timerRunning = false

        var delay = 1000

        function InitializeTimer()

        {

            // Set the length of the timer,

            // in seconds. Your choise

            secs = 1

 

            StopTheClock()

            StartTheTimer()

        }

        function StopTheClock()

        {

            if(timerRunning)

            clearTimeout(timerID)

            timerRunning = false

        }

        function StartTheTimer()

        {

            if (secs==0)

        {

            StopTheClock()

 

           // Form1.Post1 is a HTML an input button

           // on your Design form. See below.

            Form1.Post1.click()

            //Generate a Postback to the server

            InitializeTimer()

            // Start the timer again

        }

        else

        {

            secs = secs - 1

            timerRunning = true

            timerID = self.setTimeout("StartTheTimer()", delay)

        }

    }

</script>

 <INPUT id="Post1" style="Z-INDEX: 102; LEFT: 19px; POSITION: absolute; TOP: 449px" 

       type="button" value="PostBack" runat="server" onserverclick="Post1_ServerClick" visible="false" />

codebehind:

    protected void Post1_ServerClick(object sender, EventArgs e)
    {
 
    }

living life on the flip side

Re: Not Posting back

Sigurd Johansen

8:15 10 Aug '08

Hello Have you changed your body tag?
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Fix to the code

obed21

6:48 13 Aug '07

On the line of the button click change it to.... `document.forms[0].submit()` With this we dont have to create the button on the page to generate the postack. It will generate the auto postback. This is a good article by the author. Thanks for the article
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how to sending sms using asp.net vb script or c#

malake

20:58 27 Nov '06

in my project i want to send a detieles of the operation the client do it in the website as sms can you help me on it in vb or c# saeda
Sign In·View Thread·Permalink	1.50/5 (3 votes)

Solution to increasing refresh rate

isikiss

11:57 7 Aug '06

I had problem with this java script because my time ticker refresh rate increased every time it simulate the button click that refreshes my data.

The problem was found out to be excessive initialize() method calling. On the example above, it calls initialize() method after calling doc.post1.click() that causes another instance of object that ticks the timer which will eventually causing the application to refresh the data faster and faster. You don't need to call initialize() method after simulate button click that will eventually reload the page(refresh) and initialize() will be called again because it's trigged by onload() event.

for the solution for that, just remove initialize() method call under StartTheClock() function.

Cheers,

Ian Koo

New Zealand

Re: Solution to increasing refresh rate

Sigurd Johansen

10:26 7 Nov '06

Thank you Ian. That was indeed a good solution. Sigurd Johansen
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Good

venkata krishnan K S

23:23 12 Feb '06

i 've used the code & slightly done some changes & it works wonderful it is a good work
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access denied

paulains

8:55 31 Dec '05

Does anyone have a clue as to why I might be getting a JavaScript error "Access is denied" whenever I try to submit or postback automatically? The error occurs in the __DoPostBack function. Clicking on a button to submit manually works fine, but trying to do it automatically to save a step won't work. Is there a security feature I can disable? Thanks, Paul
Sign In·View Thread·Permalink	2.00/5 (4 votes)

Another easy alternative

planoie

5:53 8 Dec '05

Another option that eliminates the need to override RaisePostBackEvent: 1. Add an invisible button to the page (either in markup or programatically) 2. Use Page.GetPostBackEventReference() to emit the client-side call to fire the button's click. 3. Use the standard button click event handler in the page code behind.
Sign In·View Thread·Permalink	3.17/5 (3 votes)

Re: Another easy alternative

Umer Khan

21:46 16 May '07

can u give me a code ? thaknks alot
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XmlHttpRequest

Aquilax1

6:20 5 Dec '05

Instead of posting back the form you can use the XmlHttpRequest (javascript) to call a webservice and recive back an xml with all the data that you need to update the webpage. The XmlHttpRequest has a non blocking effect on the webbrowser, the user won't notice it, and is supported from explorer and mozilla. http://www.xulplanet.com/references/objref/XMLHttpRequest.html
Sign In·View Thread·Permalink	5.00/5 (2 votes)