pass PHP value back to AJAX function on success - php

Question

I'm building an AJAX timeline of wall posts and I have the following function to check for new posts and then post the new ones to the wall, similar to how Twitter works:
wall_posts.php
$news = tz::shared()->news->getNew(25);
<div id="wall_posts">
<?php foreach ($news as $news_post) { ?>
<div class="wall_post"><?php echo $news_post['message']; ?></div>
<?php } ?>
</div>
jQuery:
function checkForNewPosts() {
// This represents the last record in the table AKA the "most recent" news
var lastCustomerNewsID = <?php echo $news[0]['id']; ?>;
$.ajax({
url: "example.com/ajax.php",
method: "post",
data:{
lastCustomerNewsID: lastCustomerNewsID,
},
dataType:"text",
success:function(data)
{
$('#wall_posts').prepend(data);
}
});
}
setInterval(checkForNewPosts, 10000);
The news PHP array above with index 0 indicates it is the last/most recent ID in the array/table
PHP (ajax.php):
if ($_POST) {
$lastCustomerNewsID = $_POST['lastCustomerNewsID'];
$new_posts = tz::shared()->news->getNewForWall($lastCustomerNewsID);
$output = '';
if ($new_posts) {
foreach ($new_posts as $new_post) {
$output .= "<div class='wall_post'>";
$output .= $new_post['message'];
$output .= "</div>";
}
} else {
}
echo $output;
}
Note - The function getNewForWall pulls records with an id greater than the argument passed in
This works fine when getting a new post, however the problem is that I need to update the "last id" to the "newest id" from the new records returned in ajax.php each time the function runs, because currently once its grabs the newest posts the first time, its keeps recognizing those as new on an ongoing basis.
How can I pass the newest "last id" from the array in ajax.php back to the AJAX function each time it runs? Can I pass a separate variable back to the AJAX function?
Thanks!

Answer 1

First of all, I think PHP here should return JSON instead of HTML information
JQuery should process JSON to generate HTML information
The PHP code looks like this (this is an example)
<?php
$page = $_POST['page'];
$method = $_GET['method'];
if ($method == "list") {
$limit = 20;
$offset = ($page - 1) * $limit;
$post = new Post();
// Calculate offsets according to page limits and page numbers and query articles
//Let's assume that the field of content is "content"
$offset = ($page - 1) * $limit;
$post_list = $post->offset($offset)->limit($limit)->select();
$total = $post->offset($offset)->limit($limit)->count(); //Statistics of all entries
//Get the largest ID by ID sort
$last_id = $post->order('id desc')->find();
$last_id = $last_id['id'];
echo json_encode([
'last_id' => $last_id,
'post_list' => $post_list,
"maxpage"=>ceil($total / $limit), //Calculate the maximum number of pages
]);
} elseif ($method == 'last_check') {
$post = new Post();
//Get the largest ID by ID sort
$last_id = $post->order('id desc')->find();
$last_id = $last_id['id'];
echo json_encode([
'last_id' => $last_id,
]);
}
Now we can check whether there are new articles through timers and page flips.
And you can use maxpage to determine if there is the next page.
function checkForNewPosts() {
$.ajax({
url: "example.com/ajax.php?method=last_check",
method: "get",
dataType:"json",
success:function(data)
{
if(data.last_id>lastCustomerNewsID){
//Write a new post operation here.
lastCustomerNewsID = data.last_id;
}
}
});
}
function getNextPage(){
var html;
page = page + 1;
$.ajax({
url: "example.com/ajax.php?method=list",
method: "post",
data:{
"page": page
},
dataType:"json",
success:function(data)
{
//Collate JSON into the required HTML format
html = "";
$.each(data.post_list, function(i, item){
html = html + "<div class='wall_post'>" + item.contect + "</div>";
});
if(data.last_id>lastCustomerNewsID){
//Write a new post operation here.
lastCustomerNewsID = data.last_id;
}
if(data.maxpage<=page){
//If there is no next page
}
$('#wall_posts').prepend(data);
}
});
}
setInterval(checkForNewPosts, 10000);