PHP Unset Session Variable

Question

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!

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
– bbowesbo, Commented Jun 2, 2016 at 8:41
t3kz I think that would delete the entire list of products rather than one, i'll have a go — bbowesbo
– bbowesbo, Commented Jun 2, 2016 at 8:42
@BradleyBoothman so using unset($_SESSION['Products']); fixes right? — Thamilhan
– Thamilhan, Commented Jun 2, 2016 at 8:45

JSowa · Accepted Answer · 2020-10-04 11:27:33Z

146

You can unset session variable using:

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

edited Oct 4, 2020 at 11:27

JSowa

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answered Jun 2, 2016 at 8:38

Thamilhan

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3 Comments

user123456789 Over a year ago

Only use session_unset() for older deprecated code that does not use $_SESSION.

Chuck Over a year ago

What exactly is deprecated code that does not use $_SESSION ? Are there (deprecated) ways to use sessions in PHP other than $_SESSION ?

cerkes Over a year ago

unset($_SESSION['Products']); this works for me. thx

Jeff Martin · Accepted Answer · 2018-09-02 21:53:50Z

18

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.

answered Sep 2, 2018 at 21:53

Jeff Martin

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Comments

Don D · Accepted Answer · 2016-06-02 08:47:51Z

14

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 ();

answered Jun 2, 2016 at 8:47

Don D

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3 Comments

PeeHaa Over a year ago

Nitpicking here: unset is a language construct and not a function.

Don D Over a year ago

Yes. It is a language construct. But php manual itself categorize unset as a variable handling function as well. www.php.net/manual/en/ref.var.php . Any way I just needed to highlight the fact that variable name should be passed to it.

PeeHaa Over a year ago

Yes but the difference is there. It's not a function.

JRsz · Accepted Answer · 2016-06-02 08:37:43Z

11

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.

answered Jun 2, 2016 at 8:37

JRsz

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1 Comment

clockw0rk Over a year ago

$_SESSION["XYZ"] = ""; will not clear the memory. The variable will still exist, and isset() will still return true on it

mehulmpt · Accepted Answer · 2016-06-02 08:38:26Z

3

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)

answered Jun 2, 2016 at 8:38

mehulmpt

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1 Comment

PeeHaa Over a year ago

unset is not a function, but a language construct

Amin Azizzadeh · Accepted Answer · 2020-01-18 13:15:34Z

3

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(); ?>

answered Jan 18, 2020 at 13:15

Amin Azizzadeh

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Comments

David Buck · Accepted Answer · 2020-06-19 12:14:43Z

1

// set
$_SESSION['test'] = 1;

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

edited Jun 19, 2020 at 12:14

David Buck

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answered Jun 19, 2020 at 12:06

RahAlain

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1 Comment

Donald Duck is with Ukraine Over a year ago

While this code may answer the question, providing additional context regarding how and/or why it solves the problem would improve the answer's long-term value.

Omar Saade · Accepted Answer · 2022-03-19 20:35:01Z

0

$_SESSION['Poducts'] = 1; // set
unset($_SESSION['Products']); //unset

answered Mar 19, 2022 at 20:35

Omar Saade

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Comments

helvete · Accepted Answer · 2022-06-20 09:57:57Z

0

All the answer about unset are correct but one thing is needed to be corrected. If you did not use session_start() the unset() will never work. I recommend doing it this way

session_start();
unset($_SESSION['productID']);

edited Jun 20, 2022 at 9:57

helvete

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answered Jun 15, 2022 at 18:59

Unyime

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