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, Jun 02 '16 at 08:41
t3kz I think that would delete the entire list of products rather than one, i'll have a go — bbowesbo, Jun 02 '16 at 08:42
@BradleyBoothman so using `unset($_SESSION['Products']);` fixes right? — Thamilhan, Jun 02 '16 at 08:45
@BradleyBoothman So you need to hold `$_SESSION['Products']` but with empty array am I right? — Thamilhan, Jun 02 '16 at 08:51
Would you like me to show you the site im building it on? I think so though yes — bbowesbo, Jun 02 '16 at 08:55

score 138 · Accepted Answer · edited Oct 04 '20 at 11:27

138

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 04 '20 at 11:27

Jsowa

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answered Jun 02 '16 at 08:38

Thamilhan

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Only use session_unset() for older deprecated code that does not use $_SESSION. – user123456789 Mar 28 '20 at 13:57
What exactly is `deprecated code that does not use $_SESSION` ? Are there (deprecated) ways to use sessions in PHP other than `$_SESSION` ? – Chuck Mar 10 '21 at 11:50
unset($_SESSION['Products']); this works for me. thx – cerkes Oct 01 '22 at 13:32

score 15 · Answer 2 · answered Sep 02 '18 at 21:53

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.

score 14 · Answer 3 · answered Jun 02 '16 at 08:47

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 02 '16 at 08:47

Don D

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Nitpicking here: `unset` is a language construct and *not* a function. – PeeHaa Jun 02 '16 at 08:56
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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. – Don D Jun 02 '16 at 09:04
Yes but the difference is there. It's not a function. – PeeHaa Jun 02 '16 at 09:06

score 11 · Answer 4 · answered Jun 02 '16 at 08:37

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 02 '16 at 08:37

JRsz

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$_SESSION["XYZ"] = ""; will not clear the memory. The variable will still exist, and isset() will still return true on it – clockw0rk Oct 07 '20 at 15:10

score 3 · Answer 5 · answered Jun 02 '16 at 08:38

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 02 '16 at 08:38

mehulmpt

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`unset` is *not* a function, but a language construct – PeeHaa Jun 02 '16 at 09:04

score 3 · Answer 6 · answered Jan 18 '20 at 13:15

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(); ?>

score 1 · Answer 7 · edited Jun 19 '20 at 12:14

1

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

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

edited Jun 19 '20 at 12:14

David Buck

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answered Jun 19 '20 at 12:06

RahAlain

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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. – Donald Duck Jun 19 '20 at 17:11

score 0 · Answer 8 · answered Mar 19 '22 at 20:35

0

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

answered Mar 19 '22 at 20:35

Omar Saade

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score 0 · Answer 9 · edited Jun 20 '22 at 09:57

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 '22 at 09:57

helvete

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answered Jun 15 '22 at 18:59

Unyime

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PHP Unset Session Variable

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