Session error already sent out

Beffic

So I have this script that after you login, if you accidentally click on a book mark or anything like that and then return back to the home page, it will check to see if a session is in progress and if so log back in to the user page. But I get this error in my code:

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/riseofim/public_html/roi/index.php:4) in /home/riseofim/public_html/roi/index.php on line 100

I have taken measures to try and fix it but every time I try and fix it to make this not show up the auto login doesn't work anymore.

I have tried moving the session around. Taking out session_start() etc... So now I am asking what can I do to make my script still work and errors not exist?

<?php
session_name("icsession");
session_start();

if($_SESSION['userid'] != Null){
    print"<script type=\"text/javascript\">goLogin();</script>";
}
?>

bradgrafelman

The problem is stated clearly in the error message:

Beffic wrote:
output started at /home/riseofim/public_html/roi/index.php:4

Thus, the output on line #4 of index.php is preventing the session headers from being sent on line #100.

What is the purpose of outputting that string of Javascript? If the point is to redirect the user, perhaps it would be better to call [man]header/man (and then [man]exit[/man]) to use a 'Location' header redirect instead?

Beffic

Line 4 is my meta tag

bradgrafelman

Well then that's your problem - you're outputting data before you attempt to modify the HTTP headers (such as by starting a session).

Beffic

So would I go about doing what you said above?

niroshan

Hi Beffic,

Make sure to put session_start() above all the html code.

instead of != try to use isset()

<?php
session_start();
if(!isset($_SESSION['userid'])){ 
  header("Location:login.php");
}
?>
<!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>

Hope this clear things.

Best Regards,
Niroshan

Beffic

It works except I don't need it to forward the location to login.php. I need it to run a javascript function goLogin();

How would that work?

niroshan

Hi Beffic,

In that case what you can do is check the session register inside javascript,

<?php
session_start();
?>
<!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>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<script language="javascript" type="text/javascript" src="http://code.jquery.com/jquery-1.5.min.js"></script>
<script language="javascript" type="text/javascript">
$(document).ready(function(){

<?php
if(!isset($_SESSION['userid'])){ 
  print 'goLogin();';
} 
?>
});
</script>
</head>

<body>
</body>
</html>

This example assume your using jquery. Its always good idea to call this function inside $(document).ready since that make sure it wait till loading of all the html into the browser before it calls the function.

Hope this solve your problem.

Thanks,
best regards,
niroshan

Beffic

Still my end result is nothing. I can login, hit refresh and it sends me back to the main page.

niroshan

HI Beffic,

Still my end result is nothing. I can login, hit refresh and it sends me back to the main page

Why do u need to hit refresh once you logged in.Basically it should done by the system automatically...

Can you please post the your goLogin() function code

Thanks,
Best regards,
niroshan

Beffic

"Not all" websites "are created the same." If you have a look at my website it runs strictly off of JavaScript. So when you login, you are only running a JavaScript function to replace all the content on the index page.

It would be much easier to describe if you went and registered and logged in and then hit refresh. Link is below.

Anyways, after being logged in already if you hit refresh, it sends you back to the original content of the index page, not the logged in area. Which is why I was checking to see if a session was in progress and then just forward the player through the login process.

niroshan

Hi Beffic,

Thanks for the link that helped me a lot to understand your system. The problem here is JS 🙂

If i understood it correctly,
when i press login button, in the background your checking the logins and send a javascript function name (if a successful login) and eval that from client side.. rgt ?

the problem here is when some one pressed F5 after logged in, the server will send the same html file which it sent before the login. the problem with that is, that HTML doesnt contain any function call to tell the browser that this guy is already logged in and run the logged in function instead of showing the index page content.

in-order to solve this what you need to do is add some code to the index file it self.

<script language="javascript" type="text/javascript"> 
$(document).ready(function(){ 

<?php 
if(!isset($_SESSION['userid'])){ 
  print 'function you call after a successful login to render the page();'; 
} 
?> 
}); 
</script>

so now when a user hit F5 the page will comes with the function to reload the page with appropriate data.

Only change here compared to my previous code is we are calling the actual function to replace the html with the logged in area instead of goLogin()

hope this helps,

Best regards,
niroshan

Beffic

So pretty much just add a new function that loads a different script to just forward instead of making login procedures?

niroshan

Hi Beffic,

I have checked your html and i saw that you have added $(document).ready event but you dont have any reference for jquery library. The event $(document).ready wont work if your not using jquery.

Which function you`r using to load the control panel (after logged in)? you should use that function instead of 'goLogin()' in the session validation part.Here is a break down of events to make it more clear for you,

user enter login details
you submit the logins details to server.
3. Server response.

This is what we have to concentrate. I`m pretty sure you sent a javascript function name as the response (for successful login) because i see your using eval() to evaluate that function... so you have to use this function in the PHP session checking code instead of 'goLogin()'.

P.S: If i`m wrong about the server response please correct me because that the key to solve your problem.

Thanks,
best regards,
Niroshan