[Resolved] Session Variables mysteriously go away.

xhat

I'm storing a resource id in a session variable.

$_SESSION['result'] = mysql_query($query);

I've echoed out the session variable and all is well. In fact, on the first call to the page, everything works exactly as it should. The page's purpose is to list inventory items. The number of items displayed is limited to x , and navigation links are provided at the bottom of the page to move back and forth between next and previous. Pretty standard stuff.

If the user clicks Next, I call the page again using PHP_SELF.
$SERVER['PHP_SELF'] . " additional variables in query string . To debug, I echo out $SESSION['result'], and this time it comes back zero. What is destroying my session variable?

I've been using session variables successfully with other scripts, so I think I know what I'm doing... that's usually when I get into trouble.

keith73

well, we can't really debug your code if you don't post code for us to debug.

post your code for this page (replace any sensitive data with dummy values) and we'll see what's up.

my guess is either session_start isn't called or the values aren't stored properly.

one thing I just noticed is that you are storing your query's result identifier in the session. What you have to realize is that the result is just an id # that references the results of your query in the database. You aren't actually storing the results in the session.

keith

xhat

thanks for the reply.

Yes, I realize I'm just storing the id#. My assumption is that the result set persists across page requests, and all I have to do is keep using the id# to access it. However, I'm beginning to believe that as soon as the page is left, even just to go back to itself, the result set fades away.

Here's the code for your edification. Note, the include of "common.php" holds the session_start() call. The get_ad_recordset() function runs the first time the page is called, then is skipped on subsequent calls.

<?php
include "common.php";

html_header();

if($_REQUEST['run'] == "") get_ad_recordset(); 
else show_ads($_REQUEST['screen']); 

function get_ad_recordset()
{
//Query the database for all ads

switch($_REQUEST['as'])
{
	case 1:  $ad_section = '1961 Tempest Parts List';
			 break;
	case 2:  $ad_section = '1962 Tempest/LeMans Parts List';
			 break;		
	case 3:  $ad_section = '1963 Tempest/LeMans Parts List';
			 break;		
	case 4:  $ad_section = 'Pontiac (non 61-63 Tempest/LeMans) Parts List';
			 break;		
	case 5:  $ad_section = 'Non-Pontiac Car-Related Parts List';
			 break;		
	case 6:  $ad_section = 'Manuals and Literature List';
			 break;		
	case 7:  $ad_section = 'Memorabilia and Collectibles List';
			 break;		
	case 8:  $ad_section = 'Tools, Equipment and Shop Items List';
			 break;		
	case 9:  $ad_section = 'Members "Stuff for Sale" List';
			 break;		
	default: $ad_section = '';
			 break;
}

$link_id = db_connect();

if(empty($ad_section))
	$query = "SELECT * FROM advertisement";
else
	$query = "SELECT * FROM advertisement WHERE adSection = '$ad_section'";

$_SESSION['result'] = mysql_query($query);

mysql_close($link_id);
$_SESSION['thing'] = 5; //debug variable

if($_SESSION['result']) @show_ads();
else query_fail();

}

function show_ads($screen)
{
echo $_SESSION['result']; //debug statement
echo $_SESSION['thing'];  //debug statement		
if (!isset($screen)) {
  		$screen = 1;
		echo "Unset"; //debug statement
		}
		//$start = $screen * $rows_per_page;
		//$query = "SELECT * FROM advertisement ";
		//$query .= "LIMIT $start, $rows_per_page";

$rows_per_page = 10;
$rows = mysql_num_rows($_SESSION['result']);
$pages = ceil($rows / $rows_per_page);
$last_page = $rows % $rows_per_page;

if($screen != $pages) {
	for ($i = 0; $i < $rows_per_page; $i++) {
		$description = mysql_result($_SESSION['result'], $i, 0);
		echo "\$description = $description<br>\n";
	} 
}
else {
	for($i=0; $i < $last_page; $i++) {
		$description = mysql_result($_SESSION['result'], $i, 0);
		echo "\$description = $description<br>\n";
	}
}
//next two lines commented for debugging purposes i.e. reduce 
//the number of "variables" that could be screwing me up.	
	//if($screen != $pages)
		//$flag = mysql_data_seek($_SESSION['result'], ($rows_per_page + 1));

echo "<p><hr></p>\n";
// let's create the dynamic links now
	if ($screen > 1) {
  	$url = $_SERVER['PHP_SELF'] . "?run=no&screen=" . ($screen - 1);
  	echo "<a href=\"$url\">Previous</a>\n";
	}
// page numbering links now
	for ($i = 1; $i <= $pages; $i++) {
  	$url = $_SERVER['PHP_SELF'] . "?run=no&screen=" . $i;
  	echo " | <a href=\"$url\">$i</a> | ";
	}
	if ($screen < $pages) {
  	$url = $_SERVER['PHP_SELF'] . "?run=no&screen=" . ($screen + 1);
  	echo "<a href=\"$url\">Next</a>\n";
	}
}
?>

keith73

I believe php closes all connections when the script is done executing. When that happens, your result is gone.

Where is session_start being called?
Is it in common.php?
If so, post the code for common.php as well.

If you are calling it there, then perhaps the problem is just that you are trying to pass the result link which I'm pretty sure you can't do that the way you want to.

keith

xhat

common.php has a lot of sensitive data in it... it's too much of a pain to edit. Suffice to say the I know the problem doesn't lie with my call to session_start(). "Common" is included with a number of other pages I have that use session variables, and all of them work flawlessly.

It must be that the recordset is extinguished when, as you said, the script terminates. Or upon new page requests. In any event, I can't find anything on the web that talks about saving resource id's in session variables, so it must not be something that is done a lot. Looks like its back to the drawing board for me to design a new scheme for getting my records.

thanks for the help. if any brilliant schemes to accomplish this pop into your head, holla at me. Thanks again.

n00854180t

I was having a similar problem with some of my scripts. It had to do with the fact that session_start() was called in a function from an included page. I know it is a crappy solution, but I just put @session_start() on my page (it seems to fix the problem, but you have to supress the warnings).

xhat

I tried your solution. No luck.

The problem is that as soon as I click Next, the resource id# being stored in my session variable becomes zero. I can only assume that PHP destroys those things when you navigate away from the page in which it was created.

n00854180t

Like keith said above, as soon as the script is done executing the connection to mysql is closed (thus you lose the results from the query). If you want to keep the results from the query do something like this:

while ($_SESSION['resultSessVar'] = mysql_fetch_array($result)){}

I am not sure how you would use it exactly ( Like this maybe? $_SESSION['resultSessVar']['fieldNameInDb'] ?)

xhat

Thanks for the suggestions. Sorry about the double post, n00.