PHP Object Oriented Programming

A better programmer follows object oriented programming principals. It is deal with objects and easy to update the code. In this post I want to explain how to develop user registration and login system implementing with object oriented programming in PHP.

The tutorial contains a folder called include with PHP files.

login.php
registration.php
home.php
include
-- functions.php
-- config.php

Database
Sample database users table columns uid, username, passcode, name and email.

CREATE TABLE users
(
uid INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(30) UNIQUE,
password VARCHAR(50),
name VARCHAR(100),
email VARCHAR(70) UNIQUE
);

functions.php
Contains PHP code class User{} contains functions/methods.

<?php
include_once 'config.php';
class User
{
//Database connect 
public function __construct()
{
$db = new DB_Class();
}
//Registration process 
public function register_user($name, $username, $password, $email)
{
$password = md5($password);
$sql = mysql_query("SELECT uid from users WHERE username = '$username' or email = '$email'");
$no_rows = mysql_num_rows($sql);
if ($no_rows == 0)
{
$result = mysql_query("INSERT INTO users(username, password, name, email) values ('$username', '$password','$name','$email')") or die(mysql_error());
return $result;
}
else
{
return FALSE;
}
}
// Login process
public function check_login($emailusername, $password)
{
$password = md5($password);
$result = mysql_query("SELECT uid from users WHERE email = '$emailusername' or username='$emailusername' and password = '$password'");
$user_data = mysql_fetch_array($result);
$no_rows = mysql_num_rows($result);
if ($no_rows == 1)
{
$_SESSION['login'] = true;
$_SESSION['uid'] = $user_data['uid'];
return TRUE;
}
else
{
return FALSE;
}
}
// Getting name
public function get_fullname($uid)
{
$result = mysql_query("SELECT name FROM users WHERE uid = $uid");
$user_data = mysql_fetch_array($result);
echo $user_data['name'];
}
// Getting session 
public function get_session()
{
return $_SESSION['login'];
}
// Logout 
public function user_logout()
{
$_SESSION['login'] = FALSE;
session_destroy();
}

}
?>

registration.php
Here $user = new User(); is the class User{} object using this calling method$user->register_user{} and inserting values.

<?php
include_once 'include/functions.php';
$user = new User();
// Checking for user logged in or not
if ($user->get_session())
{
header("location:home.php");
}

if ($_SERVER["REQUEST_METHOD"] == "POST")
{
$register = $user->register_user($_POST['name'], $_POST['username'], $_POST['password'], $_POST['email']);
if ($register)
{
// Registration Success
echo 'Registration successful <a href="login.php">Click here</a> to login';
} else
{
// Registration Failed
echo 'Registration failed. Email or Username already exits please try again';
}
}
?>
//HTML Code
<form method="POST" action="register.php" name='reg' >
Full Name
<input type="text" name="name"/>
Username
<input type="text" name="username"/>
Password
<input type="password" name="password"/>
Email
<input type="text" name="email"/>
<input type="submit" value="Register"/>
</form>

login.php
Calling method $user->check_login{} for login verification. 

<?php
session_start();
include_once 'include/functions.php';
$user = new User();
if ($user->get_session())
{
header("location:home.php");
}

if ($_SERVER["REQUEST_METHOD"] == "POST")
{
$login = $user->check_login($_POST['emailusername'], $_POST['password']);
if ($login)
{
// Login Success
header("location:login.php");
}
else
{
// Login Failed
$msg= 'Username / password wrong';
}
}
?>
//HTML Code
<form method="POST" action="" name="login">
Email or Username
<input type="text" name="emailusername"/>
Password
<input type="password" name="password"/>
<input type="submit" value="Login"/>
</form>

home.php

<?php
session_start();
include_once 'include/functions.php';
$user = new User();
$uid = $_SESSION['uid'];
if (!$user->get_session())
{
header("location:login.php");
}
if ($_GET['q'] == 'logout')
{
$user->user_logout();
header("location:login.php");
}
?>
//HTML Code
<a href="?q=logout">LOGOUT</a>
<h1> Hello <?php $user->get_fullname($uid); ?></h1>

config.php
Database configuration class DB_class() function __construct() is the method name for the constructor. 

<?php
define('DB_SERVER', 'localhost');
define('DB_USERNAME', 'username');
define('DB_PASSWORD', 'password');
define('DB_DATABASE', 'database');
class DB_Class 
{
function __construct()
{
$connection = mysql_connect(DB_SERVER, DB_USERNAME, DB_PASSWORD) or
die('Oops connection error -> ' . mysql_error());
mysql_select_db(DB_DATABASE, $connection)
or die('Database error -> ' . mysql_error());
}
}
?>

How to add new function/method.

For example if you want to get email value. Just include the following function inside class User{} 

public function get_email($uid)
{
$result = mysql_query("SELECT email FROM users WHERE uid = $uid");
$user_data = mysql_fetch_array($result);
echo $user_data['email'];
}

Print email values.

<?php $user->get_email($uid); ?>