The only way is by using AJAX. Here's an example.
//////////////////////////////////////////////////////////////////////////
// Page1.aspx
//////////////////////////////////////////////////////////////////////////
<script type="text/javascript">
<!--
var g_databaseRecordKey = '<%= DatabaseRecordKey %>';
var g_isPostBack = false;
function callAjax(webUrl, queryString)
{
var xmlHttpObject = null;
try
{
// Firefox, Opera 8.0+, Safari...
xmlHttpObject = new XMLHttpRequest();
}
catch(ex)
{
// Internet Explorer...
try
{
xmlHttpObject = new ActiveXObject('Msxml2.XMLHTTP');
}
catch(ex)
{
xmlHttpObject = new ActiveXObject('Microsoft.XMLHTTP');
}
}
if ( xmlHttpObject == null )
{
window.alert('AJAX is not available in this browser');
return;
}
xmlHttpObject.open("GET", webUrl + queryString, false);
xmlHttpObject.send();
var valueSent = xmlHttpObject.responseText;
return valueSent;
}
function doUpdate()
{
var webUrl = 'AjaxPage.aspx';
// Add any additional values needed for the update to the QueryString...
var queryString = '?CallRequest=UpdateDatabase&DbKey=' + g_databaseRecordKey;
var returnCode = callAjax(webUrl, queryString);
//alert('returnCode: ' + returnCode);
}
function windowOnUnload()
{
if ( g_isPostBack == true )
return; // Let the page unload
//alert('window.onunload fired');
doUpdate();
}
window.onunload = windowOnUnload;
// -->
</script>
//////////////////////////////////////////////////////////////////////////
// Page1.aspx.cs
//////////////////////////////////////////////////////////////////////////
protected string DatabaseRecordKey = "";
protected void Page_Load(object sender, EventArgs e)
{
// Set to the unique database record key for this user...
DatabaseRecordKey = "1234";
this.ClientScript.RegisterOnSubmitStatement(this.GetType(), "OnSubmitScript", "g_isPostBack = true;");
}
//////////////////////////////////////////////////////////////////////////
// AjaxPage.aspx.cs
//////////////////////////////////////////////////////////////////////////
protected string UpdateDatabase(string dbKey)
{
string returnValue = "OK";
// Update the database here setting the returnValue variable to "Failed" if not successful...
return returnValue;
}
private void Page_Load(object sender, System.EventArgs e)
{
string callRequest = (this.Request["CallRequest"] == null) ? string.Empty : this.Request["CallRequest"];
string returnValue = string.Empty;
if ( callRequest == "UpdateDatabase" )
{
string dbKey = (this.Request["DbKey"] == null) ? string.Empty : this.Request["DbKey"];
returnValue = UpdateDatabase(dbKey);
}
this.Response.ClearHeaders();
this.Response.Clear();
this.Response.Write(returnValue);
this.Response.End();
}
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