How to keep session alive without reloading page? - php

Question

I have a strange problem in my online test management system.
Some users in the test form (test.php) need long time to answer the question and submit the form.
After submitting the form the session is expired and user must login again
this is not a code problem
I set this value in top of all pages
ini_set('session.gc_maxlifetime', 18000);
Is there a way to refresh the session evrey 10 minutes without reloading the page in test form to prevent session expire?
Please help me
Thanks

Answer 1

You can use javascript XHR, or as others call it, AJAX.
http://api.jquery.com/jQuery.ajax/
http://api.jquery.com/jQuery.get/
Using ajax you can call a php script that refreshes your session every 10 minutes. :)
This is as far as i can go to "exact".
javascript
var refreshSn = function ()
{
var time = 600000; // 10 mins
setTimeout(
function ()
{
$.ajax({
url: 'refresh_session.php',
cache: false,
complete: function () {refreshSn();}
});
},
time
);
};
// Call in page
refreshSn()
refresh_session.php
<?php
session_start();
// store session data
if (isset($_SESSION['id']))
$_SESSION['id'] = $_SESSION['id']; // or if you have any algo.
?>
Anyway, another solution would be to extend the session time for the test page only using
the solution presented here
How do I expire a PHP session after 30 minutes?

Answer 2

All you need is this (uses jQuery for the $.post):
JavaScript (put this inside your onload-function or something)
setInterval(function(){
$.post('path/to/refresh_session.php');
},600000); //refreshes the session every 10 minutes
refresh_session.php
<?php
session_start();
// if you have more session-vars that are needed for login, also check
// if they are set and refresh them as well
if (isset($_SESSION['token'])) {
$_SESSION['token'] = $_SESSION['token'];
}
?>
The biggest change is in the JavaScript--you don't need a whole function, just one line.
EXTRA INFO
Although I think it's enough to just call session_start() in the php, if I read this right (http://nl3.php.net/function.session-start):
The read callback will retrieve any existing session data (stored in a
special serialized format) and will be unserialized and used to
automatically populate the $_SESSION superglobal when the read
callback returns the saved session data back to PHP session handling.
And during testing I only put the above code on my visitor page, and not on the admin page. But I had both pages open in the same browser (Chrome), and the admin page stayed logged in as well, at least for over an hour (didn't check any longer).
BUT, I don't know if it still works if you only use session_start(), without manually refreshing any session-var at all..
Either way, I like to be sure that the session-vars I need are really still there:)

Answer 3

Javascript:
function doStayAlive() {
var request = new XMLHttpRequest();
request.open('GET', 'stayalive.php', true);
request.send();
}
timerStayAlive = setInterval(doStayAlive, 600000); // 10 minutes
PHP: (stayalive.php)
<?php
session_start();
http_response_code(204);
?>
There is no need to "touch" session variables