PHP local variable check - php

Question

I am working with a set of variables that i check each time a page loads. I have successfully checked through $_REQUEST and $_SESSION, but am having trouble with the dynamci checking of variables assigned higher int he page, if they were set.
the following is my code:
$important_field = array('treatmentId','category','state','providerId','sellDoc','insuranceName','grossCharge','discount','allowable','patientPortion','insurancePortion','dateOfService','billFileLocation','eobFileLocation','fromTable');
foreach ($important_field as $key) {
if (!$$key || $$key == "none" || $$key == "" || $$key == NULL) {
if (!$_REQUEST[$key] || $_REQUEST[$key] == "" || $_REQUEST[$key] == NULL) {
if (!$_SESSION[$key]) {
// wow, guess it just wasn't set anywhere...
} else {
$user->sell->$key = $_SESSION[$key];
}
} else {
$user->sell->$key = $_REQUEST[$key]; $_SESSION[$key] = $_REQUEST[$key];
}
} else {
$user->sell->$$key = $$key; $_SESSION[$$key] = $$key;
}
}
Apparently evaluating $$key does not seem to do what i'm looking for as it never assigns the variable to the session... how should I be evaluating the $key to get the currently set value of say, field $eobFileLocation if it was already set in the PHP prior to the check?
Thanks,
Silver Tiger
Update:
ok, i have the following code, but there's still one bug with it. When i follow my process through af ew of these variables are set on each page and are carried over by the session variable as expected. The issue I am still having is that when i submit a new $_REQUEST variable which SHOULD change the session variable to the new submitted value, the script is finding a local variable ... where is it pulling $key and $$key from that is finding these as a local variable?
$important_field = array('treatmentId','category','state','city','providerId','sellDoc','insuranceName','grossCharge','discount','allowable','patientPortion','insurancePortion','dateOfService','billFileLocation','eobFileLocation','fromTable');
foreach ($important_field as $key) {
if (isset($$key) && !empty($$key) && $$key != "none") {
echo "Found local variable for ".$key.", i'll set the session and user to this.<br>\n";
$user->sell->$key = $$key;
$_SESSION[$key] = $$key;
} elseif (isset($_REQUEST[$key]) && !empty($_REQUEST[$key])) {
echo "Found submitted form variable for ".$key.", i'll set the session and user to this.<br>\n";
$user->sell->$key = $_REQUEST[$key];
$_SESSION[$key] = $_REQUEST[$key];
} elseif (isset($_SESSION[$key]) && !empty($_SESSION[$key])) {
echo "Found a session variable ".$key.", i'll set the user to this.<br>\n";
$user->sell->$key = $_SESSION[$key];
} else {
echo "There was no provided data for ".$key."<br>\n";
}
}
Any ideas why when i load the page it thinks the local (as listed above) is set? does $key and $$key read from $_SESSION['blah']/$_REQUEST['blah'] and think it's just $blah?

Answer 1

Are you sure this is what you want:
$user->sell->$$key = $$key;
should it not be
$user->sell->$key = $$key;
try using the empty function:
if (empty($$key) || $$key == "none")
if (empty($_REQUEST[$key]))
and the isset function:
if (!isset($_SESSION[$key]))

Answer 2

it is
$user->sell->$key = $$key;
not
$user->sell->$$key = $$key;
and
$_SESSION[$$key]
should be
$_SESSION[$key]

Answer 3

You're messing with your variables, this is not good. In fact, using two var signs ($$) describes a "variable variable".
$foo = "name";
$$foo = "value";
So you expect the following:
echo $foo; // => "name"
echo $$foo; // => "value"
What you maybe are not expecting, is:
echo $name; // => "value"
So you're better off cleaning up your code first.

Answer 4

Well, I have expressed my concerns about the cleanliness of this approach in the comments. Here's at least some more compact code without variable variables to do the same thing:
$keys = array('treatmentId', 'category', ...)
$values = array_filter(array_merge(
array_intersect_key($_SESSION, array_flip($keys)),
array_intersect_key($_REQUEST, array_flip($keys)),
compact($keys)
), function ($v) { return $v && $v != 'none'; });
$_SESSION = array_merge($_SESSION, $values);
foreach ($values as $key => $value) {
$user->sell->$key = $value;
}
// For debugging purposes:
//
// $diff = array_diff_key(array_flip($keys), $values);
// if ($diff) {
// 'No values for ' . join(', ', array_keys($diff));
// }