How to show users that a new comment has been entered - php

Question

I have a small blog that I am creating. It gets its information from a database. I would like to show the users that are logged in that someone else has just entered a new comment. I have created 3 pages: old_count, new_count, posts. I was going to create a session for both new_count and old_count and subtract them in posts. The result would have been displayed in a div to the user. This idea I have scrapped because both old_count and new_count would have the same information, so the result in posts would have always been 0. What I am looking for is something like Twitter where if there is a new entry, a div appears displaying --1 New post--. I have being looking for a way to do this. Can someone please help me. (Note - please explain script given in full....Thanks In Advance!!!!)

Answer 1

Set a timestamp of the last time they checked for content.
then, using javascript, poll the server (SELECT * FROM posts WHERE created_timestamp > {$last_checked_timestamp}
If result > 0 then display count.
Update timestamp.

Answer 2

The question is: When is a comment a new comment? If it has been created between the most recent click and the current click? Or if the user has not yet seen it?
The easiest way will be to store the "known" comments (e.g. IDs) in the session and check against the currently available comments.

Answer 3

You would have to store the login timestamp user. Maybe in DB or in session. Check it against the comment timestamp.
You have to display notifications for all the comments that have been inserted in the database and stick to following conditions
Comment_Timestamp < User_Login_Timestamp.
(Current_Timestamp - Comment_Timestamp) <= Refresh_interval
PHP:
<?php
/*
DB CONNECT AND SQL TO SELECT COMMENTS FROM THE TABLE. YOU CAN OPTIMIZE QUERY TO REDUCE THE NUMBER OF
TUPLES
*/
$current_ts = strtotime(date('m/d/Y h:i:s a');
$notified = array();
foreach($all_comments as $comment) {
if(strtotime($comment['ts']) < strtotime($_SESSION['user_login_ts'])) {
if(($current_ts - strtotime($comment['ts']) <= REFRESH_INTERVAL) {
$notified[] = $comment;
}
}
}
echo json_encode($notified);
?>
JS AJAX
setInterval(function(){
$.ajax({
url: "server",
success: function(data) {
/* Data is the JSON Object for new comments for that user */
},
dataType: "json"
});
}, <?=REFRESH_INTERVAL?>);

Answer 4

With the suggestion that was posted by David, I came up with the following solution to the questions that I had asked earlier.
I created a timestamp upon login.
I then use this to run the search on the database.
The DIV containing this information is being refresh every 10 secs and is a clickable link to a timestamp reset page. The code for this page is as follows:
<?php
session_start();
$reset = $_POST['reset'];
if($reset == 'reset')
{
$_SESSION['time_stamp'] = time();
echo "done";//confirmation purpose
}
?>
and my javascript that controls the whole show:
<script type="text/javascript">
<!--
$(document).ready(function(){
$('#divname').click(function(){
var r="reset";
$.ajax({
type: "POST",
url: "reset_time.php",
data: r,
success: function(html){
if(html == 'done')
{
$('#divwithinfo').reload(/*my blog page url*/);
}
});
});
});
-->
</script>