OnUnload code firing on pageload in ASP.NET C#

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I am preparing a webpage in asp.net using c#

I want certain code to be executed on page load and some other code to be executed on page unload. My code is as follows:

C#

protected void Page_Load(object sender, EventArgs e)
    {
        if(!IsPostBack)
        {
            //code to be executed on page load when user enter the page           
        }
   }

// Other code for execution depending on user requirement 

protected override void OnUnload(EventArgs e)
    {
            base.OnUnload(e);
        
            // code to be executed on user leaves the page    
   }

My problem is that the code for unload gets fired on pageload itself whereas I expect only pageload code to fire at page load and pageunload code to fire only when user leaves the page.

Kindly help me by advising what I am missing in the code

Many thanks for help

Posted 14-Feb-15 5:58am

Member 10235977

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Anisuzzaman Sumon · Answer 1 · 2015-02-14T21:24:00

Solution 1

With AutoEventWireup which is turned on by default on a page you can just add methods prepended with Page_event and have ASP.NET connect to the events for you.

In the case of Unload the method signature is:

C#

protected void Page_Unload(object sender, EventArgs e)

So you need to write:

C#

protected void Page_Load(object sender, EventArgs e)
    {
        if(!IsPostBack)
        {
            //code to be executed on page load when user enter the page           
        }
   }
 
// Other code for execution depending on user requirement 

protected void Page_UnLoad(object sender, EventArgs e)
    {
            // code to be executed on user leaves the page    
   }

Posted 14-Feb-15 21:24pm

Anisuzzaman Sumon

Updated 14-Feb-15 21:28pm

v2

Comments

Member 10235977 15-Feb-15 6:17am

Thanks Sir but it has still not worked for me as Page_UnLoad code still fires on page load itself. I wonder if the code page_UnLoad has to be nested in some command like if(!IsPostBack) as done in Page_Load method. I have tried nesting in if(!IsPostBack) and also if(!IsCallBack) but it does not seem to work. Apparently I need a little more elaboration. Kindly help.

Anisuzzaman Sumon 15-Feb-15 6:25am

Show More code or You may use flag in if(!IsPostBack){
flag=true;
}

And then check the flag before executing the code inside Page_UnLoad . like protected void Page_UnLoad(object sender,EventAgrs e){ if(!flag){ //code to be executed on user leaves the page} }

Member 10235977 15-Feb-15 8:14am

My code for page load is:

protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
using (SqlConnection con = Connections.GetConnection())
{
SqlCommand com = new SqlCommand("UPDATE OnOffStatus SET Status=@Status", con);
com.Parameters.AddWithValue("@Status", "on");
com.ExecuteNonQuery();
con.Close();
}
}
}

And my Page UnLoad code is

protected void Page_UnLoad(object sender, EventArgs e)
{

using (SqlConnection con = Connections.GetConnection())
{
SqlCommand com = new SqlCommand("UPDATE OnOffStatus SET Status=@Status", con);
com.Parameters.AddWithValue("@Status", "off");
con.Close();
}

}

I have not been able to use 'flag= true', as I get the error that the name 'flag' does not exist in the current context.

I shall be highly grateful for your help for your help in solving this issue.

Anisuzzaman Sumon · Answer 2 · 2015-02-15T17:44:00

Actually Page_UnLoad event is rasied when the page is rendered and loaded completely at the end of its page life cycle.It is not just like you have done through form_closing event in windows form application.Instead you can detect browser close event and then call server side event using ajax.As shown like below

JavaScript

<script type="text/javascript">
$(function () {
    $(window).unload(function () {

   jQuery.ajax({ url: "http://localhost:49591/yourwebform.aspx", async: false });
      });
});
</script>

If you have not used it before just ask google.Happy coding!:)