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What is session ?
A normal HTML website will not pass data from one page to another. In other words, all information is forgotten when a new page is loaded. A PHP session solves this problem by allowing you to store user information on the server for later use (i.e. username, Password). However, this session information is temporary and is usually deleted very quickly after the user has left the website that uses sessions. Session handling is a key concept in PHP that enables user information to be persisted across all the pages of a website or app. A PHP session is used to store data on a server rather than the computer of the user.
Starting a PHP session
Before you can begin storing user information in your PHP session, you must first start the session. When you start a session, it must be at the very beginning of your code, before any HTML or text is sent.
<?php session_start(); // start up your PHP session ?>
Storing a session data
When you want to store user data in a session use the $_SESSION associative array. This is where you both store and retrieve session data.
<?php session_start(); $_SESSION['name'] = "xyz"; // store session data echo "Name = ". $_SESSION['name']; //retrieve data ?>
Output
Name= xyz
php sessions: using php’s isset function
explore some of the real functionality of sessions. When you create a variable and store it in a session, you probably want to use it in the future. However, before you use a session variable it is necessary that you check to see if it exists already. This is where PHP’s isset function comes in handy. isset is a function that takes any variable you want to use and checks to see if it has been set. That is, it has already been assigned a value.
<?php session_start(); if(isset($_SESSION['name'])) echo "Name = ". $_SESSION['name']; else $_SESSION['name'] = "xyz"; ?>
Cleaning and Distroying your session
Although a session’s data is temporary and does not require that you explicitly clean after yourself, you may wish to delete some data for your various tasks.
Cleaning your session
<?php session_start(); if(isset($_SESSION['cart'])) unset($_SESSION['cart']); ?>
Distroying your session
You can also completely destroy the session entirely by calling the session_destroy function.
<?php session_start(); session_destroy(); ?>
PHP login with session
Login.php
<html> <head> <title>Login Form</title> </head> <body> <h2>Login Form</h2> <form method="post" action="checklogin.php"> USER ID: <input type="text" name="uid"/><br> PASSWORD: <input type="password" name="pw"/><br> <input type="submit" value="Login"/> </form> </body> </html>
checklogin.php
<?php
session_start();
$uid = $_POST['uid'];
$pw = $_POST['pw'];
if($uid == 'arun' and $pw == 'arun123')
{
$_SESSION['sid'] = '$uid'; # need to set user id instead of session_id()
if (isset($_SESSION['sid'])) {
header('Location: welcome.php');
}
else
{
echo "Error";
}
}
?>
welcome.php
<?php
session_start();
if(isset($_SESSION['sid']))
{
echo "welcome to you<br>";
echo "<a href='logout.php'>Logout</a>";
}
else
{
header('Location: login.php');
}
?>
logout.php
<?php
session_start();
if(!session_destroy())
{
echo "Failed to log out";
}
else
{
echo "Logged out successfully";
}
?>