send_message.php

<?php
// Message sending is only possible over HTTP POST and when the user is logged in
require './includes/http_method_post.php';
require './includes/logged_in.php';

// When a message was sent and it's not empty, insert it to the database with appropriate user information
if($_POST['message'] != ''){
    $query = "INSERT INTO public.chat_message (user_id, message) VALUES (:user_id, :message)";
    $query_params = array(':user_id' => $_SESSION['user_id'], ':message' => $_POST['message']);
    try{
        $stmt = $pdo->prepare($query);
        $result = $stmt->execute($query_params);
    }
    catch(PDOException $ex){
        // Fail early when a error occurs
        echo '<span style="color: red">ERROR! Code: 011</span>';
        exit;
    }
}
?>