PHP Unset Session Variable

58
votes

I'm a noob programmer so I apologies in advance for any obvious mistakes. I've spent the past week creating a product database kinda thing. I've got too the point where I can add products using a form, view all products added etc. I've being using sessions which are created via the form input data. I'm struggling to include get a delete product page working, I've tried using unset to clear the variable but can't get it too work.

ADD Product page which sets the session variable: 

$_SESSION['Products'][] = $_POST; //is how i set the session on the add products page. 

unset $_SESSION['Products'][]; //is how i have tried to clear the session although it does not work.

Any point in the right direction will be appreciated!

7
phpsession
unset($_SESSION['Products']); is enough - Thamilhan
and to clear all session's use session_unset(); - Bram B
Giving it a bit of thought I think I would need to do more than unset the session variable. I would need to delete the entire array for that product from my product list page. My bad - bbowesbo
t3kz I think that would delete the entire list of products rather than one, i'll have a go - bbowesbo
@BradleyBoothman so using unset($_SESSION['Products']); fixes right? - Thamilhan

7 Answers

120
votes

You can unset session variable using:

  1. session_unset - Frees all session variables (It is equal to using: $_SESSION = array(); for older deprecated code)
  2. unset($_SESSION['Products']); - Unset only Products index in session variable. (Remember: You have to use like a function, not as you used)
  3. session_destroy — Destroys all data registered to a session

To know the difference between using session_unset and session_destroy, read this SO answer. That helps.

14
votes

Unset is a function. Therefore you have to submit which variable has to be destroyed. 

unset($var);

In your case 

unset ($_SESSION["products"]);

If you need to reset whole session variable just call

session_destroy ();
11
votes

I am including this answer in case someone comes to this page for the same reason I did. I just wasted an embarrassing amount of time trying to track the problem down. I was calling:

unset($_SESSION['myVar']);

from a logout script. Then navigating to a page that required login, and the server still thought I was logged in. The problem was that the logout script was not calling:

session_start();

Unsetting a session var DOES NOT WORK unless you start the session first.

8
votes

If you completely want to clear the session you can use this:

session_unset();
session_destroy();

Actually both are not neccessary but it does not hurt.

If you want to clear only a specific part I think you need this:

unset($_SESSION['Products']);
//or
$_SESSION['Products'] = "";

depending on what you need.

3
votes

unset is a function, not an operator. Use it like unset($_SESSION['key']); to unset that session key. You can, however, use session_destroy(); as well. (Make sure to start the session with session_start(); as well)

3
votes

Destroying a PHP Session

A PHP session can be destroyed by session_destroy() function. This function does not need any argument and a single call can destroy all the session variables. If you want to destroy a single session variable then you can use unset() function to unset a session variable.

Here is the example to unset a single variable 

<?php    unset($_SESSION['counter']); ?>

Here is the call which will destroy all the session variables 

<?php    session_destroy(); ?>
1
votes
// set
$_SESSION['test'] = 1;

// destroy
unset($_SESSION['test']);