PHP Sessions

Sometimes we need to create a website that need sessions to know if a user is logged or not, or other data we need between pages.

session_start()

We can start a session anytime with session_start() or resume the existing one.

<?php
session_start();

Recuerde que las sesiones se utilizan para guardar datos de la sesión mientras esta está abierta.

$_SESSION

An associative array containing session variables available to the current script

php.net

In the following case I can say that I’m assigning ELPEPE value to session name variable

<?php
session_start();
$_SESSION['name']="ELPEPE";

¿When to use session variables?

An example could it be when a user login in our page.

You could save data from the user on $_SESSION, these data could it be the name, a token or something that distinguish the user, so we could know where the user has access.

I not recommend to store personal user data on sessions like password or something like that. Could store email if its necessary but not make it public on your page.

session_destroy()

Destroy all info associated with the actual session but not destroy variables associated with the session, also do not destroy the session cookie.

If we call session_start() again after a session_destroy() we can access $_SESSION[‘name’] value becouse we do not unset it.

To eliminate this data we can use unset()

<?php
session_start();
unset($_SESSION['name']);
session_destroy();

In this way we can eliminate $_SESSION[‘name’] variable

IMPORTANT: Never use unset on $_SESSION.

Session functions

1- session_name (since PHP 4)— obtain or establish the actual session name

2- session_id (since PHP 4)— obtain or establish the actual session id

3- session_cache_expire (since PHP 4.2)

4- session_abort(since PHP 5.6.0 and PHP 7) discard all changes in session array and end the session

5- session_gc (since PHP 7.1)— session garbage collection

Deprecated Functions

$HTTP_SESSION_VARS Contain all variables in session, instead use $_SESSION

session_is_registered – we can check a session with isset() so this function has no sense

session_register – Register one or more global variables with the current session actually we use $_SESSION[‘var_name’]

session_unregister -actually we use unset()