unset all session variables in form

SundariDevi

I have a form that uses session variables. If the user makes an error filling out the form, the form will be displayed again with an error message, and the php script repopulates all the fields that a user has entered so they don't need to be entered again.

But i think session variables can't be overwritten by $_POST , right? So I need to unset all the session variables after the form is repopulated, so if the user changes something the new values will be saved.

If i use this, it works correctly:

session_unregister("var1");
session_unregister("var2");

But I want to loop through the whole set of variables. So I make an array of all the variables in the form, store it in $formVars and try to unregister them. This doesn't work, the variables don't get unset:

for ( $i = 0; $i < count($formVars); $i++ )
	{
	session_unregister($formVars[$i]);
	}

What is the correct way to do this, or a better way?

NogDog

Easiest way:

$_SESSION = array();

PS: This assumes that you are, in fact, using $_SESSION and not the antiquated and deprecated session_register() and session_unregister() functions?

SundariDevi

Thanks! I thought it would be easy to upgrade 5 year old code, after not using php for a long time, but I guess I have to do more work!

Weedpacket

Well, the code might be five years old, but the style is ten years old 🙂

SundariDevi

It's updated now.

$_SESSION = array();

Actually, this doesn't work it seems like it's erasing all the variables from the session even on a successful post.

I call it at the bottom of the form, so when a new form is loaded it has no effect, when a user is redirected due to form filling our errors, the session variables repopulate the fields and then at the bottom of the script they should get reset.

bradgrafelman

SundariDevi;10993981 wrote:
Actually, this doesn't work it seems like it's erasing all the variables from the session even on a successful post.

..well then that means it is working, since that's exactly what you're telling PHP to do.

SundariDevi;10993981 wrote:
I call it at the bottom of the form, so when a new form is loaded it has no effect, when a user is redirected due to form filling our errors, the session variables repopulate the fields and then at the bottom of the script they should get reset.

Can you show us the PHP code you've got now?

SundariDevi

I have a lot of code...

Basically for this problem, it is a two page form (two html pages that call one php script). After the first page is successfully processed I need to store all those variables somewhere and then go to the second page of the form to get more variables.

Right now, when I go to the 2nd page, if there is an error all the good variables from the first page get erased too. If I unset them one at a time like i was doing, that didn't happen. I guess if I output the two form pages from the same script the variables will stay in scope so I can copy them to an array. But I would rather not change to that right now.

So I need to store the validated variables from the first page somewhere or on error just reset the session variables from the second page and leave the variables from the first page untouched.

bradgrafelman

You could group the data from the two pages in an array in the session, that way you could selectively unset a single page's worth of form data.

SundariDevi

Right now I do this

After first page is submitted

	foreach($_POST as $varname=>$value)
        {
	   $_SESSION[$varname]=$value;
            $allVars[$varname]=$value;
        }

then if all the variables are valid

	// store validated data in $allVars
	$_SESSION['allVars']=$allVars;

Now I go to the 2nd page of the form.
If there is an error in the form submission, all the session variables are unst, including the $allVars which has the first page variables.

If I did something like this, I could unset all but $allVars

for ( $i = 0; $i < count($SESSION); $i++ )
{
if ($varname <> "allVars")
session_unregister($SESSION[$i]);
}

But that didn't work in the code I had using the old session method.

bradgrafelman

For one, don't use [man]session_register/man at all (for obvious reasons if you visit the manual page for it).

For another, why not try my suggestion above? There's no need for a loop - you could simply store the entire $_POST array at once, e.g.:

$_SESSION['pages'][0] = $_POST;

where the 0 index would change from one page to the next. That way, if you wanted to unset the data from the first page, you'd simply do:

unset($_SESSION['pages'][0]);

which would leave the data from all other pages untouched.

SundariDevi

Thanks that looks like what I need. I'll try it.