Nsryjdtyk

I have a messages table that stores messages between users.Using the following i show messages based on the users and when users click load more messages are fetch with offset:

        $offset      = $_POST['offset'];

        $limit       = 10;



$stmt = $db_con->query("SELECT sender,recipient,sending_time,read_time,CASE WHEN LENGTH(content) > 7 THEN CONCAT(substring(content, 1, 49), '...') ELSE content END content,recipient_status FROM messages WHERE (sender='admin' OR recipient='admin') ORDER BY sending_time DESC LIMIT $offset,$limit");

            $stmt->execute();

            $db_messages = $stmt->fetchAll(PDO::FETCH_ASSOC);

        $total_posts = ceil($db_count("messages","id","WHERE (sender='admin' OR recipient='admin')","")[0]);

        $MSGS_array  = array();

        $MSGS        = '';          

        $posts       = abs($offset-$limit);



        foreach($db_messages as $key => $value) {

            if($value['sender']=='admin'){$my = $value['recipient']; }else if ($value['recipient']=='admin'){ $my =$value['sender']; }else { $my=$value['sender'];}

            $messages = array("user"=>$my,"sending_time"=>$value['sending_time'],"read_time"=>$value['read_time'],"content"=>$value['content'],"recipient_status"=>$value['recipient_status']);   

        }

        foreach ($messages as $message) {

            $MSGS_array[$message['user']] = $message;

        }

        $non_unique_users = array_filter(array_count_values(array_column($messages, 'user')), function ($v) { return $v != 1; });

        $duplicates = array_filter($messages, function ($v) use($non_unique_users) { return array_key_exists($v['user'], $non_unique_users); });

        //setcookie("username", "John Carter", time()+30*24*60*60);

        foreach($MSGS_array as $key => $message){

            $MSGS   .= '<li><a id="'.$message['user'].'" class="view-headerMSG list-group-item b-rad-0 p10 b0 m0"><div class="online-users pull-left mr5"><img src="../uploads/userprofile/default/avatar.jpg" onerror="this.onerror=null;imgDefault(this);" alt="avatar" class="online-users-img"><span title="online"></span></div><strong class="text-primary h4 mb2">'.$message['user'].'<small class="pull-right">'.$ToReadableTime('@'.$message['sending_time']).'</small></strong><div><small class="text-muted">'.$message['content'].'</small></div></a></li>';

        }

        echo json_encode(['MSGS' => $MSGS,"posts" => $posts,"total_posts" => $total_posts,"duplicates"=>$MSGS_array]);

WHAT THE CODE DOES?

On page load, ajax request sent to php for fetching messages with the offset 0 and limit 10 .The 1st foreach loop creates an array and the 2nd foreach remove duplicates having key 'user' .

But when i click load more, next 10 messages are fetched (as in the first fetch duplicated messages were removed and i have stored the duplicated/removed keys and values in $duplicates). These messages also contains those messages which were already fetched and appended to the messagebox.

The logic i have in my mind is when fetching first time(i.e offset 0) the $duplicates should be stored in cookie and then after that when the fetch is made with offset greater than 0(such as 10) then the cookie value should be merged with $messages array using array_merge and then the similar values should be unset /deleted and this is the part where i don't know how can i unset ?

OR

is there any way we can compare the cookie value(that is an array of multidimensional) with the $MSGS_array from which the duplicated values have been removed and in the comparison we can do something like unsetting/deleting the key and value that are similar?

Any suggestions ?