Message Board Part 2 Snippets

Session start script for top of messageboard.php file

session_start();

if (isset($_GET['logoff']))
{
	session_destroy();
	session_start();
}

Last ID session variable check

if(!isset($_SESSION['lastID']))
{
	$query = "SELECT * FROM messages order by id desc limit 1";
	$result = mysqli_query($link, $query);
	$row = mysqli_fetch_row($result);
	$_SESSION['lastID'] = $row[0];
}

The new get_messages function

function get_messages($link)
{
	$lastID = $_SESSION['lastID'];
	$query = "select * from messages where id = '$lastID'";
	$result = mysqli_query($link, $query);
	
	if(mysqli_num_rows($result) == 1)
	{
		$row = mysqli_fetch_row($result);
		list($id, $name, $message, $datetime)=$row;
		
		echo "<div>";
		echo "<p>";
		echo "<strong>$name: </strong>";
		echo "$message";
		echo "</p>";
		echo "</div>";
	
		$_SESSION['lastID']++;
	}
}

Process.php file...

<?php 

define ("DB_HOST", "localhost");
define ("DB_USER", "root");
define ("DB_PWORD", "root");
define ("DB_NAME", "messageboard");

$link = new mysqli(DB_HOST, DB_USER, DB_PWORD, DB_NAME);
if ($link->connect_errno)
{
	echo "Failed to connect to MySQL: (" . $link->connect_errno . ") " . $link->connect_error;
}

function process_form($link)
{
	if(isset($_POST['name']))
	{
		$name = $_POST['name'];
		$message = $_POST['message'];
		$query = "insert into messages values('', '$name', '$message', NOW())";
		mysqli_query($link, $query);
	}
}
process_form($link);

if( isset($link) )
{
	mysqli_close($link);
}

?>

Display.php file...

<?php session_start();

if (isset($_GET['logoff']))
{
	session_destroy();
	session_start();
}

define ("DB_HOST", "localhost");
define ("DB_USER", "root");
define ("DB_PWORD", "root");
define ("DB_NAME", "messageboard");

$link = new mysqli(DB_HOST, DB_USER, DB_PWORD, DB_NAME);
if ($link->connect_errno)
{
	echo "Failed to connect to MySQL: (" . $link->connect_errno . ") " . $link->connect_error;
}

if(!isset($_SESSION['lastID']))
{
	$query = "SELECT * FROM messages order by id desc limit 1";
	$result = mysqli_query($link, $query);
	$row = mysqli_fetch_row($result);
	$_SESSION['lastID'] = $row[0];
}

function get_messages($link)
{
	$lastID = $_SESSION['lastID'];
	$query = "select * from messages where id = '$lastID'";
	$result = mysqli_query($link, $query);
	
	if(mysqli_num_rows($result) == 1)
	{
		$row = mysqli_fetch_row($result);
		list($id, $name, $message, $datetime)=$row;
		
		echo "<div>";
		echo "<p>";
		echo "<strong>$name: </strong>";
		echo "$message";
		echo "</p>";
		echo "</div>";
	
		$_SESSION['lastID']++;
	}
}

get_messages($link);

if( isset($link) )
{
	mysqli_close($link);
}

?>

The loadMessages function...

function loadMessages()
{
	var newMessage = $.ajax({ type: "GET", url: "display.php", async: false }).responseText;
	
	if(newMessage.length > 0)
	{
		$("#messages").prepend(newMessage);
		$("#messages div:first").hide();
		$("#messages div:first").fadeIn(2000);
	}
}

Capturing the return or enter key...

$('#message').keypress(function(event){
	if (event.which == 13)
	{
		$('#myform').submit();
		event.preventDefault();
	}

});

Deleting old messages - add to the process_form function

$lastID = mysqli_insert_id($link);
$oldMessages = $lastID - 20;
$delete_query = "delete from messages where id < '$oldMessages'";
mysqli_query($link, $delete_query);

Safe function

function safe($link, $value) 
{
	$value = trim($value);
	$value= mysqli_real_escape_string($link, $value);
	return $value;
}

Final process_form function

function process_form($link)
{
	if(isset($_POST['name']))
	{
		$name = safe($link, $_POST['name']);
		$message = safe($link, $_POST['message']);
		$query = "insert into messages values('', '$name', '$message', NOW())";
		mysqli_query($link, $query);
		
		$lastID = mysqli_insert_id($link);
		$oldMessages = $lastID - 20;
		$delete_query = "delete from messages where id < '$oldMessages'";
		mysqli_query($link, $delete_query);
	}
}