PHP [PHP] Letting your visitors know that some pages have changed ...

Hi all,

Sometimes, it can be useful to let your visitors know that something has changed on one page or the other of your website. Since I am not a big fan of cookies, I'll propose a small PHP/MySQL implementation that simply assumes that your visitor is identified via a session variable "user_id", you can of course adapt this to your need.

Code is split in two parts:
1 - monitoring a page that is subject to changes
2 - getting this information to present in a menu

1 - monitoring a page that is subject to changes

In each page you want to track, import the corresponding lib and provide a unique ID, as a variable $trackId. For instance in my page storing the latest news, in PHP I declare :

$trackId = "news";
@require_once("track.php");

Signal the system that user has just visited current page :

handleTrack($trackId);

Whenever you decide that your page has changed and should show up accordingly in menu, just use :

updateTrack($trackId);

2 - getting this information to present in a menu

In the menu page where you want to monitor which pages contain new stuff, use, add part in red in the menu item corresponding to the tracked page :

<li><a <?= newStyle("news") ?> href="/news.php">News</a></li>

Method "newStyle", present in track.php, will detect if your user has already seen the latest version of this page, and display something accordingly.

In this example, I force the style to change to "new_menu_item", but you're of course encouraged to use your style instead

3- that's it ! Now a little big on the technical part ...

Track.php assumes that you have a MySQL table with the following format :

user_id : int(4)
page : text
time : timestamp

The track.php file follows (for clarity I'm using methods "executeSQL" and "getData", you may replace them with whatever code you access your database with) :

<?php

function trackUser($trackId, $userId) {
executeSQL("delete from track where user_id=".$userId." and page='".$trackId."'");
executeSQL("insert into track (user_id, page, time) values (".$userId.",'".$trackId."', now())");
}

function updateTrack($trackId) {
trackUser($trackId, -1);
}

function handleTrack($trackId) {
if (($trackId != null) && isset($_SESSION['user_id'])) {
// user is visiting a tracked page

trackUser($trackId, $_SESSION['user_id']);
}
}

function isNew($trackId) {
$result = 0;
$update = null;
$last = null;

if (isset($_SESSION['user_id'])) {
// last change timestamp

$rs = executeSQL("select * from track where page='".$trackId."' and user_id=-1");

if ($data = getData($rs)) {
$update =$data["time"];
}

// last visit timestamp

$rs = executeSQL("select * from track where page='".$trackId."' and user_id=".$_SESSION['user_id']);

if ($data = getData($rs)) {
$last =$data["time"];
}

// result

if (($update != null) && ($last == null) || ($update > $last)) {
$result = 1;
}
}

return $result;
}

function newStyle($trackId) {
$result = "";

if (isNew($trackId)) {
$result = "class='new_menu_item'";
}

return $result;
}
?>