Finally, for the sake of completeness, below I listed all the classes that I used for constructing the previous example:

// define 'User' class
class User{
    var $name;
    var $address;
    var $email;
    function User($userData=array()){
        if(!is_array($userData)){
            trigger_error('User data must be an
array!',E_USER_ERROR);
        }
        foreach($userData as $property=>$value){
            if($property==''||$value==''){
                trigger_error('Invalid values for user
data!',E_USER_ERROR);
            }
            $this->{$property}=$value;
        }
    }
    // obtain user name
    function getName(){
        return $this->name;
    }
    // obtain user address
    function getAddress(){
        return $this->address;
    }
    // obtain user email
    function getEmail(){
        return $this->email;
    }
}
// define 'ObjectSerializer' class
class ObjectSerializer{
    function ObjectSerializer(){}
    function getSerializedObj($obj){
        if(!is_object($obj)){
            trigger_error($obj.'input parameter must be an
object!',E_USER_ERROR);
        }
        return serialize($obj);
    }
    function getUnserializedObj($data){
        if(!is_string($data)){
            trigger_error($data. 'must be a
string!',E_USER_ERROR);
        }
        return unserialize($data);
    }
}
// define 'MySQL' class
class MySQL {
    var $conId; // connection identifier
    var $host; // MySQL host
    var $user; // MySQL username
    var $password; // MySQL password
    var $database; // MySQL database
    // constructor
    function MySQL($options=array()){
        // validate incoming parameters
        if(count($options)>0){
            foreach($options as $parameter=>$value){
                if(empty($value)){
                    trigger_error('Invalid parameter
'.$parameter,E_USER_ERROR);
                }
                $this->{$parameter}=$value;
            }
            // connect to MySQL
            $this->connectDB();
        }
        else {
            trigger_error('No connection parameters were
provided',E_USER_ERROR);
        }
    }
    // connect to MYSQL server and select database
    function connectDB(){
        if(!$this->conId=mysql_connect($this->host,$this-
>user,$this->password)){
            trigger_error('Error connecting to the
server',E_USER_ERROR);
        }
        if(!mysql_select_db($this->database,$this->conId)){
            trigger_error('Error selecting
database',E_USER_ERROR);
        }
    }
    // perform query
    function query($query){
        if(!$this->result=mysql_query($query,$this->conId)){
            trigger_error('Error performing query
'.$query,E_USER_ERROR);
        }
        // return new Result object
        return new Result($this,$this->result); 
    }
}
// define 'Result' class
class Result {
    var $mysql; // instance of MySQL object
    var $result; // result set
    function Result(&$mysql,$result){
        $this->mysql=&$mysql;
        $this->result=$result;
    }
    // fetch row
    function fetchRow(){
        return mysql_fetch_array($this->result,MYSQL_ASSOC);
    }
    // count rows
    function countRows(){
        if(!$rows=mysql_num_rows($this->result)){
            return false;
        }
        return $rows;
    }
    // count affected rows
    function countAffectedRows(){
        if(!$rows=mysql_affected_rows($this->mysql->conId)){
            trigger_error('Error counting affected
rows',E_USER_ERROR);
        }
        return $rows;
    }
    // get ID from last inserted row
    function getInsertID(){
        if(!$id=mysql_insert_id($this->mysql->conId)){
            trigger_error('Error getting ID',E_USER_ERROR);
        }
        return $id;
    }
    // seek row
    function seekRow($row=0){
        if(!mysql_data_seek($this->result,$row)){
            trigger_error('Error seeking data',E_USER_ERROR);
        }
    }
    function getQueryResource(){
        return $this->result;
    }
}

To wrap up

We’re done now. Over this series, I covered not only the fundamentals of object serialization in PHP, but also some advanced topics, such as the implementation of the magic “__sleep()” and “__wakeup()” functions, and the usage of objects in sessions. Finally, I completed the series by demonstrating how to store serialized objects in MySQL tables, which makes me believe that you have enough code to keep you experimenting for many hours. As usual, see you in the next PHP tutorial!