PHP - Reloading URL with a GET variable - php

Question

I would like to ensure that a $_GET variable is set to the value of another variable in my URL. If not then i would like to reload the page/url to show a set variable. This is the code im using:
session_start();
$openfile = $_SESSION['openfile'];
//check if $GET variable isset to the current $SESSION variable
if($_GET['file'] !== $_SESSION['openfile'] && !empty($_SESSION['openfile'])){
//if not then create new URL string
$hloc = basename($_SERVER['PHP_SELF']).'?file='.$openfile;
//change location to new URL string
header("Location: $hloc");
}
i dont understand why it doesn't work.
Any help would be great. Thanks.
edit: the problem is that the url doesn't reflect that of what the header info should be. this fixes itself fine if the page is then reloaded again. however, this is clearly not what I want.

Answer 1

if(isset($_GET['file'])) {
//its set means value is not equal to null or false
} else {
//its not set so redirect
}
http://php.net/manual/en/function.isset.php

Answer 2

Can you provide an example URL so we can see if that is coking it? Barring that, try this instead. Note how the $hloc is now outside the quotes:
session_start();
//check if $GET variable isset to the current $SESSION variable
if($_GET['file'] !== $_SESSION['openfile'] && !empty($_SESSION['openfile'])){
//if not then create new URL string
$hloc = basename($_SERVER['PHP_SELF']).'?file='.$openfile;
//change location to new URL string
header("Location: " . $hloc);
}

Answer 3

There is a mistake. Undefined variable: openfile.
Change this line
$hloc = basename($_SERVER['PHP_SELF']).'?file='.$openfile;
to
$hloc = basename($_SERVER['PHP_SELF']).'?file='.$_SESSION['openfile'];
As $openvariable is set(according to poster comment), so only fault is:
Either SESSION variable or GET variable is not set.Since the following code works perfectly.
<?php
session_start();
$_SESSION['openfile']='foo';
$_GET['file']='bar';
$openfile = $_SESSION['openfile'];
//check if $GET variable isset to the current $SESSION variable
if($_GET['file'] !== $_SESSION['openfile'] && !empty($_SESSION['openfile'])){
//if not then create new URL string
$hloc = basename($_SERVER['PHP_SELF']).'?file='.$openfile;
//change location to new URL string
header("Location: $hloc");
}
?>
As syntactically your code looks perfect,thus check properly whether Both GET Variable and Session Variable is set or not.
First Comment this statement header("Location: $hloc"); temporarily.
Put:
echo $_GET['file'];
echo $_SESSION['openfile'];
before if condition and check the output.It will help you to trace and know bug.

Answer 4

i found the problem.
it was due to having incorrect header information further down the script.