从$ _SERVER ['REQUEST_URI']命名$ _SESSION var会神秘地命名页面“blank.gif”

Seems like such a simple problem but I'm out of options here...

So I want to set up a session variable that tells me the last page visited. I thought I could do this by declaring 2 session variables in a php include at the top of every page.

    session_start();    
    if(!$_SESSION['this_url']){
           // will only be declared once
           $_SESSION['this_url'] = $_SERVER['REQUEST_URI'];
        }

        if($_SERVER['REQUEST_URI'] != $_SESSION['this_url']){ //dont update var on page refresh
           $_SESSION['last_url'] = $_SESSION['this_url']; 
           $_SESSION['this_url'] = $_SERVER['REQUEST_URI'];  
        }

Simple enough right? But for an output it gives me this:

$_SESSION['this_url'] = /support/interactive.php (correct)

$_SESSION['last_url'] = /products/compatibility/blank.gif (right path, but blank.gif? wtf?)

it SHOULD be outputting "/products/compatibility/somepage.php" but it always replaces the page name with blank.gif.

I did a sitewide search on my site and nothing else is using my variable names. I even changed the var names and still same result. blank.gif is found in some jQuery scripts - so I suspect this may be where its coming from. But still... I'm declaring these things as the first piece of script on the page and outputting them immediately after declaring them. Is my Apache server messed up or what? this doesnt make sense.

Any ideas would be greatly appreciated, thanks!

Hmm, I remember trying to do something like this a while back, and I was having odd ghost problems much like you. What I ended up doing was using hidden inputs and assigning the variables to them.

I'm not saying use hidden form elements for production, I'm just making a suggestion in case the feature you are creating is a "need now" kind of feature.

I'm still looking as to why that may happen though, what version of Apache/PHP are you running?