Page expiring and back buttons

[Tailslide]

Hi all

I'm slightly confused (as per normal) and wondering if you could help.

I have a page - let's call it advice.php.

When a user clicks a link on that page it goes to an intermediary checking page which checks which link they want to go to, records their visit in the DB and then sends them to the requested page is on external sites.

That page is called checklinks.php.

Trouble is when users are on the external page and hit back button they get the expired page warning in IE (and re-send page warning in FF).

I've tried adding

ini_set('session.cache_limiter', 'private'); 

to the checklinks.php page which I thought was working but I seem to occasionally get a repetition of the problem.

What's the best way around this and have I added that ini_set() to the right page - should it have been on the advice.php page (the original page).

Thanks

[AnthonySterling]

If I follow, you're basically implementing the POST/Redirect/GET Pattern, but without the POST.

Page.php -> Logger.php -> Target

I always thought you just have to send the right HTTP code for this to work?

header('HTTP/1.1 303 See Other');
header('Location: http://www.somesite.com/');
exit; 

Edit: Yup, just tested here FF3 and all seems good.

[crmalibu]

Check which actual http headers get sent on that page. An easy way is to use a browser addon like http live headers or firebug for firefox.

[Tailslide]

Yes it's one of those things that's hard to explain - the basic idea is that the client is passing leads onto another company and needs to keep track of where the people that use the site are going - they have passwords which enable them to log in and once logged in they can then access the links to the other companies.

The links go to the checking page and have the particular company id appended to them.

The checking page makes a note of the user and where they're going and then redirects them according to the supplier id appended to the URL of the link on the first page.

Does that make sense?

[Keeton]

Sounds a lot like what I do at http://linktrack.info.

Here's how I approach it:

Use a tracking hash on each link and have your redirect page look for it in the url and check for it in the database of links.

If it's a valid link, record the visit in the database and use php header() to foward them to the proper location.

[Tailslide]

Hi Keeton

Is there an advantage in hashing the link identifier bit as opposed to just having an id in the url which checks against the db and re-directs? Would it stop the expired page thing?

[AnthonySterling]

Morning Tailslide,

Does my offering not suit?

I tried it here and did not receive any expired page notices, are you POSTing to the intermediate page or simple passing an id via GET?

HTML

<a href="redirect.php?id=1">Visit</a>

PHP(redirect.php)

<?php
$aSites = array(
    'http://www.google.co.uk',
    'http://www.yahoo.co.uk',
    'http://news.bbc.co.uk',
    'http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/',
);
if(isset($_GET['id']) && !empty($_GET['id']) && isset($aSites[$_GET['id']]))
{
    header('HTTP/1.1 303 See Other');
    header(
        sprintf(
            'Location: %s',
            $aSites[$_GET['id']]
        )
    );
    exit;
}
?>

[Tailslide]

Hi Anthony

Been out of the office so haven't had a chance to try it!

I'll give it a go this morning and see if I have any joy.

Thanks for your help.

this is a shortened version of my script with your header bit added in - does it look right?

if($_GET['supplier_id'])
{
$supplier_id=$_GET['supplier_id'];

... other bits retrieving supplier link url from db and adding stuff to db about the person clicking through ...

header("Location:". $sup_link);
header('HTTP/1.1 303 See Other');

} 

[AnthonySterling]

Switch-a-roo those header calls and you're good to go I'd say.

[Tailslide]

Cool - thanks. Having the day from hell at the moment but will get this done asap and let you know.

[Tailslide]

Hmmm... odd...

It's still happening, but only on the first "clickthrough" once logged in. Far as I can see it doesn't repeat itself after that. But if I logout and log back in - again the first link I try, when I then hit "Back" I get the expired webpage warning.

[Tailslide]

Are there any other suggestions with this problem as I have to see the client later on today!

Thanks for your patience.