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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!

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  • 15
    unset($_SESSION['Products']); is enough Commented Jun 2, 2016 at 8:34
  • 2
    and to clear all session's use session_unset(); Commented Jun 2, 2016 at 8:37
  • Giving it a bit of thought I think I would need to do more than unset the session variable. I would need to delete the entire array for that product from my product list page. My bad Commented Jun 2, 2016 at 8:41
  • t3kz I think that would delete the entire list of products rather than one, i'll have a go Commented Jun 2, 2016 at 8:42
  • @BradleyBoothman so using unset($_SESSION['Products']); fixes right? Commented Jun 2, 2016 at 8:45

9 Answers 9

Reset to default
146

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.

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3 Comments

Only use session_unset() for older deprecated code that does not use $_SESSION.
What exactly is deprecated code that does not use $_SESSION ? Are there (deprecated) ways to use sessions in PHP other than $_SESSION ?
unset($_SESSION['Products']); this works for me. thx
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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.

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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 ();
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3 Comments

Nitpicking here: unset is a language construct and not a function.
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.
Yes but the difference is there. It's not a function.
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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.

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

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unset is not a function, but a language construct
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(); ?>
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1 
// set $_SESSION['test'] = 1; // destroy unset($_SESSION['test']);
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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.
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$_SESSION['Poducts'] = 1; // set unset($_SESSION['Products']); //unset
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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']);
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