serialize() and $_SESSION [duplicate]

Question

Once the user is authenticated, I serialized the class object and stored it in a session. However, I cant seem to print its output even after using unserialize().

Creating the session variable:

if(!isset($_SESSION['myObj']) && empty($_SESSION['myObj'])) {
$myObj = new User($row['user_id'], $row['username'], $row['user_level']);
$_SESSION['username']= $myObj->usr_name;
$s_Obj = serialize($myObj);
$_SESSION['myObj'] = $s_Obj;

Accessing from a different page, no output:

$sObj = $_SESSION['Obj'];
$myObj = unserialize($s_Obj);
echo $myObj->usr_name;

This works however, so there's nothing wrong with my class. I am also using session_start() in both pages.

echo $_SESSION['username'];

Class user:

<?php 

class User{
    public $usr_id;
    public $usr_name;
    public $usr_level;
    public $last_access_login;

    public function __construct($id, $usr_name, $usr_level) {
        $this->usr_id = $id;
        $this->usr_name = $usr_name;
        $this->usr_level = $usr_level;
        $this->last_access_login = date("F d Y H:i:s.",time());
  }
}
?>

Edit:

This is my vardump

array
  'myObj' => 
    object(__PHP_Incomplete_Class)[1]
      public '__PHP_Incomplete_Class_Name' => string 'User' (length=4)
      public 'usr_id' => string '3' (length=1)
      public 'usr_name' => string 'student' (length=7)
      public 'usr_level' => string '3' (length=1)
      public 'last_access_login' => string 'November 26 2011 20:12:38.' (length=26)
  'url' => string '/researchportal/proposal' (length=24)

Answer 1

Inital page:

$s_Obj = serialize($myObj);
$_SESSION['myObj'] = $s_Obj;

should be

$_SESSION['myObj'] = $myObj;

Next page:

$sObj = $_SESSION['Obj'];
$myObj = unserialize($s_Obj);

should be

$myObj = $_SESSION['myObj'];

In addition, try declaring your classes before your call to session_start().

Answer 2

Your unserialized object is being unserialized as an instance of __PHP_Incomplete_Class_Name because you are not including the definition of the User class prior to unserializing it. See Object Serialization. You must include the definition of the User class before you try to unserialize it.