PHP isset($_SESSION[$var]) Not working at all

Question

In my project, I have a wrapper class for $_SESSION, so session variables can be accessed by $session->var. I was trying to check if session variables were set or not using isset:

if (!isset($this->session->idUser)) {
    ...
}

but isset is not returning anything. So in my wrapper class I wrote the following function to test what was going on.

public function isItSet($var)
{
   die(isset($_SESSION["id"]));
}

this results in an empty page. I tried:

public function isItSet($var)
{
    die(is_null(isset($_SESSION["id"])));
}

still an empty page. Then I tried:

public function isItSet($var)
{
    die(isset($_SESSION));
}

This returns 1.

Can anyone tell me why trying to check if a session variable is set returns nothing?

Answer 1

To support isset() you need to overload the function in your wrapper.

So, in your wrapper, add:

public function __isset($var){
  return isset($_SESSION[$var]);
}

To use it, you just have to do:

isset($this->session->myVar);

If it is still not working, do:

var_dump($_SESSION)

This will dump the whole $_SESSION array and show you whether the variable you are checking for actually exists.

Answer 2

In my opinion, issue is related to testing and not with PHP session.

The MAIN REASON behind why session variable isset returns nothing is use of die() function which is equivalent to exit() according to PHP manual itself.

http://in1.php.net/die

So, use var_dump() instead.

Answer 3

Your results are basically correct.

The boolean values being pass to each function just confused you i think.

Heres a clear explainations what happens to each of your statement.

LETS GET IT ONE BY ONE

// declaring this array as a set of session being passed as sample.
$string = array('name'=>'kaii');

echo die(isset($string['id'])); // figure 1
// step
// isset($string) returns a value of false because of unexistent of an array with the name of id.
// die(false)   returns nothing because of the value being passed by isset is false.
// result would be definitely empty

echo die(is_null(isset($string['id']))); // figure 2
// step
// isset($string) returns a value of false because of unexistent of an array with the name of id.
// is_null(false) returns a value of false because it only accepts NULL as its parameter value to return true.
// die(false)   returns nothing because of the value being passed by is_null is false.
// result would be definitely empty


echo die(isset($string)); //figure 3
// step
// isset($string) returns a value of true because of a $string variable is set and exist.
// die(true)    returns a value of 1 because of the value being passed is true which is equivalent to 1 .
// result would be definitely return a value of 1.

note: In general your statement is correct just a few justification is needed to support it.

---

Additional:

print_r(),var_dump()

• use it to check your session if it has a name that youre trying to declared.

A brief explanation:

isset()

• returns a boolean value of true or false

is_null()

• accepts only a NULL parameter value to return a boolean value of true else it goes false.

die()

• returns a value of 1 for true and empty value for false.

Reasons:

• A boolean TRUE value is converted to the string "1". Boolean FALSE is converted to ""

Answer 4

isset returns an empty page because your variable does not exist in session, so isset return false, however, echo false return ''.
It was already written in the commentary to hakre

You can test this like that:

echo "false : " . false . "\n";
echo "true : " . true . "\n";

=>

false : 
true : 1

So, for your test, do a var_dump($_SESSION) and you will see if it is normal that isset($_SESSION['id']) returns false.

You can also test: die("false : " . (false == isset($_SESSION['id'])));