Question

I’m building a basic forum where every post contains some text, first and last name, and the date the message was written.
I’d like to have the board update with AJAX constantly, and to add new messages on the fly as they are written.
I have a file, getlatest.php?date=... that retrieves all messages from the date in the $_GET till NOW().
It returns the data as an array of objects. Lastly, I JSON-encode the data.
I call this function from some AJAX code, like so:

 setInterval("update()", 5000);
                function update(){
                    $.get("getlatest.php", {
                        date: "2009-06-23_16:22:12" //this is just a date I
                                                    //entered for testing
                    }, function(forumdata){
                                           //do something with forumdata here?
                    }, "json");
                }

Now I have the data within forumdata, as in forumdata[0].first_name ect.

I would like to now use PHP to display the comment, like so:

$forumdata = json_decode(forumdata);
foreach ($forumdata as $value)
{
    $newpost = new Post($value); // Post being some class that gets the data from 
                                 // $value and converts it to HTML + CSS
    $newpost->displayPost();     // some function that echo's the HTML
}

I realize what I’m trying to accomplish here is slightly unfeasible, since PHP is a server-side language, and the calculations are at this point client-side, but is there some way (maybe through AJAX?) that I could use PHP to manage the data, once I retrieve it through javascript?

My main reason for wanting to do this is my total lack of knowledge in javascript, so any alternatives for translating the forumdata variable into blocks of HTML and CSS are also great for me.

Answer 1

Well since you don’t want to use too much JavaScript (don’t be scared with the popular Libraries and Frameworks it is acutally a pretty easy thing to learn and can save you a lot of the hassle you would have by managing everything on the server side) you can still output just the HTML without decoding it to JSON.
So the client does this:

 setInterval("update()", 5000);
                function update(){
                    $.get("getlatest.php", {
                        date: "2009-06-23_16:22:12" //this is just a date I
                                                    //entered for testing
                    }, function(forumdata){
                                           //do something with forumdata here?
            // e.g.
            $("#forum_entries").prepend(forumdata);
                    }, "html");
                }

And the PHP script (getlatest.php) just does this:

<?php
$forumdata = find_posts_after_date($_GET('date'));
foreach ($forumdata as $newpost)
{
   // Echos just the post specific HTML not a whole HTML page
    $newpost->displayPost();     // some function that echo's the HTML  
}
?>

As nerdling already suggested you should not use the Date but the latext Unique ID of the post the client is currently displaying.