how to unset session variables with a certain prefix

Question

Possible Duplicate:
How to unset/destroy all session data except some specific keys?

I am having certain session variables starting with "cars" such as

$_SESSION["cars_registration"];
$_SESSION["cars_make"];
$_SESSION["cars_model"];
$_SESSION["cars_variant"];
.
.
.
$_SESSION["cars_date_created"];

I want to know the code for unsetting / deleting / emptying only those session variables which starts with cars as prefix like above.

So far I have achieved this but dont have any idea about code for unsetting them.

foreach($_SESSION as $key => $value)
{
    if (strpos($key, 'cars_') === 0)
    {
      // Need to delete / unset the session variables  
    }
}

Please help me with it

Whats's wrong with `unset($_SESSION[$key])` ? – Rikesh Dec 31 '12 at 10:50 — Rikesh, Dec 31 '12 at 10:50

DaveRandom · Answer 1 · 2012-12-31T11:08:18.693

Well, I'm glad to see that php is still capable of ignoring the glaringly obvious.

There are many ways that you can do this with loops and all sorts of things, however the right way to do this would be to use a sub array cars, which you can easily destroy in one go.

So instead of creating

$_SESSION["cars_registration"];
$_SESSION["cars_make"];

etc, you would create:

$_SESSION["cars"]["registration"];
$_SESSION["cars"]["make"];

So when you come to unset it, you simply need to do:

unset($_SESSION["cars"]);

$_SESSION can hold data in a multi-dimensional structure just like any other array - it does not need to be a flat collection of values.

+1, I was thinking just this, why not make cars an array. – kittycat Dec 31 '12 at 10:59 — kittycat, Dec 31 '12 at 10:59

Netorica · Accepted Answer · 2012-12-31T10:53:55.080

4

you almost got it!!!

 foreach($_SESSION as $key => $value)
    {
        if (strpos($key, 'cars_') === 0)
        {
          unset($_SESSION[$key]); //add this line
        }
    }

here are some few explanations. inside the foreach you set $key to be a variable to hold the key of the $_SESSION array for each iteration and it works the same with the $value

reference:

http://php.net/manual/en/control-structures.foreach.php

edited Dec 31 '12 at 10:53

answered Dec 31 '12 at 10:51

Netorica

18,523
17
73
108

There is a good reason for using `===`. `strpos` returns `FALSE` if needle was not found. `strpos('cats_registration', 'cars_')` will return `FALSE` and `FALSE == 0` and the key be removed when it should not. – Salman A Dec 31 '12 at 10:55
@SalmanA just revised my answer thank you – Netorica Dec 31 '12 at 10:57
@Mahan - thnks for the help buddy – Asnexplore Jan 01 '13 at 19:13

score 3 · Answer 3 · answered Dec 31 '12 at 10:51

3

Just use unset.

foreach($_SESSION as $key => $value)
{
    if (strpos($key, 'cars_') === 0)
    {
      unset($_SESSION[$key]);
    }
}

answered Dec 31 '12 at 10:51

Michael

930
5
8

score 0 · Answer 4 · answered Dec 31 '12 at 10:52

session_unregister — Unregister a global variable from the current session This function has been DEPRECATED as of PHP 5.3.0. Relying on this feature is highly discouraged.

session_unset — Free all session variables Do NOT unset the whole $_SESSION with unset($_SESSION) as this will disable the registering of session variables through the $_SESSION superglobal.

session_destroy — Destroys all data registered to a session

score 0 · Answer 5 · answered Dec 31 '12 at 10:53

0

With PHP, you can use unset to 'destroy' a variable. So, once you're convinced the key meets your criteria you can do:

unset($_SESSION($key));

answered Dec 31 '12 at 10:53

Grant Thomas

44,454
10
85
129

how to unset session variables with a certain prefix

5 Answers5