[RESOLVED] Track Visited Links via Setcookie?

technovore

I posted this to the Newbies forum, but it's not yielding any specific replies, so I thought I'd try here.

I have a simple flat-file-based PHP forum, and I want to be able to keep track of which links (messages) each user has visited, so that when they return later, the state of each link can be set as they last saw it. I'm going to use setcookie to write the information to a cookie, but I'm not sure what PHP code to use to record which links the user has clicked (and how to set the links to appear "visited" when the info is later read back from the cookie.)

wilku

I don't think you can change the state of the link "as browser sees it". So you can't rely on default browser behavior for visitet links. You have to use different css for read and unread messages when you display your page in php.
Be careful with storing read mesages in cookies as they have limited size (I don't remember the limit). But it happend to me on some busy forum, where cookie held messages id's like 1;3;4;6;467;... and at some moment it started throwin out messages about too big cookies to accept.

technovore

wilku wrote:
I don't think you can change the state of the link "as browser sees it". So you can't rely on default browser behavior for visitet links. You have to use different css for read and unread messages when you display your page in php.
Be careful with storing read mesages in cookies as they have limited size (I don't remember the limit). But it happend to me on some busy forum, where cookie held messages id's like 1;3;4;6;467;... and at some moment it started throwin out messages about too big cookies to accept.

Thanks for your reply. The forum is very low-usage, so I'm not too concerned about the message IDs creating a huge cookie. What I have in mind is creating alternative link styles for "read" and "unread" in my CSS and assigning them dynamically to the links via PHP, based on which message IDs are stored in the user's cookie. That way the default (or custom) browser behavior isn't an issue. Again, what I don't know how to do is A. Capture the link name when a user clicks on that link and B. Read the cookie data (link names) back in and use it to dynamically assign styles to those links before displaying the index page.

wilku

Data stored in cookies can be accessed via $COOKIE['name']. This is for reading. For writing to the cookie use [man]setcookie[/man]
A. When displaying message:
- check if the message id is in $COOKIE['read']
- if it is not there, append it to received cookie data and send back using setcookie
B. When displaying links, get $_COOKIE['read'] and check which id's are there.

I would store the id's as name: read, value: id1;id2;id3;...
Then the array of read id's can be obtained with

$read_id = explode(";",$_COOKIE['read']);
//check if id is in a table
if (in_array("id",$read_id)) echo 'class="read"';
else echo 'class="unread"';

When you want to add id to the array:

if (!in_array("id",$read_id)) setcookie("read",$_COOKIE['read'].";id",time()+$nr_of_seconds_to_store_information);

technovore

wilku wrote:
Data stored in cookies can be accessed via $COOKIE['name']. This is for reading. For writing to the cookie use [man]setcookie[/man]
A. When displaying message:
- check if the message id is in $COOKIE['read']
- if it is not there, append it to received cookie data and send back using setcookie
B. When displaying links, get $_COOKIE['read'] and check which id's are there.
<snip>

That's exactly what I was looking for, thanks! The only thing I'm unclear on now is how the "add to array" if statement gets called when the user clicks a link.

wilku

Adding takes place not when the user clicks a link, but when the target page is echoed. If you want to track external links, when your script isn't running on external page, you need to do a kind of redirection. Instead of giving link to target, give link to the redirect.php and inside redirect.php set new cookie and then use [man]header[/man] to send Location header (redirect to target page).

technovore

Yes, that makes perfect sense. I see now that your answer A above was telling me the same thing. Since I only need to track internal links (forum message pages displayed by the script) the redirect shouldn't be necessary. Thanks again for your help!

I will give this idea a try in the few days and see if I can implement it correctly.

bradgrafelman

Don't forget to mark this thread resolved (if it is).