Using Object Oriented Programming to store User values

Question

I'm using Object Oriented Programming to store User values to be used throughout a website. However i'm getting stuck on one particular issue. I'm trying to create a feature within a class that gets the User's values (after they login) to be stored to the Class instantiated. So far all the methods in the Class executes and the session becomes 'Logged-in' which is great. But the values I've tried to obtain from the User is not storing to the attributes within the Class.

class Users {

public $User_ID;     
public $Password;
public $First_name;
public $Surname;
public $Email;
public $User_lvl;

public static function authenticate($Email, $Password) {
global $database;
$sql  = "SELECT * FROM Users ";
$sql .= "WHERE Email = '{$Email}' ";
$sql .= "AND Password = '{$Password}' ";
$sql .= "LIMIT 1";
self::find_by_sql($sql);
$result_array = self::find_by_sql($sql);
    return !empty($result_array) ? array_shift($result_array) : false;
  }


public static function find_by_sql($sql="") {
global $database;
$result_set = $database->query($sql);
$object_array = array();
while ($row = $database->fetch_array($result_set)) {
  $object_array[] = self::instantiate($row);
    }
 return $object_array;
}

public function fetch_array($result_set) {
return mysqli_fetch_array($result_set);
 }

private static function instantiate($row) {
$object = new self;
    foreach($row as $attribute=>$value){
      if($object->has_attribute($attribute)) {
        $object->$attribute = $value;
      }
    }
return $object; 
}

private function has_attribute($attribute) {
  $object_vars = get_object_vars($this);
  return array_key_exists($attribute, $object_vars);
}

Also the class does not seem to become instantiated as a trying to call a non-static function from the Class does not work. So the values aren't being obtained and the class isn't being instantiated. Please could anyone help me with this issue I'd appreciate it very much.

Answer 1

I prepare for you OOP classes that you can work with.

1. Move the global to DBService base class.

2. Change the self call to user instance.

   class User {
   
       private $userId;
       private $password;
       private $firstName;
       private $surname;
       private $email;
       private $userLevel;
   
       function __construct($userId, $password, $firstName, $surname, $email, $userLevel) {
           $this->userId = $userId;
           $this->password = $password;
           $this->firstName = $firstName;
           $this->surname = $surname;
           $this->email = $email;
           $this->userLevel = $userLevel;
       }
   
       function getUserId() {
           return $this->userId;
       }
   
       function getPassword() {
           return $this->password;
       }
   
       function getFirstName() {
           return $this->firstName;
       }
   
       function getSurname() {
           return $this->surname;
       }
   
       function getEmail() {
           return $this->email;
       }
   
       function getUserLevel() {
           return $this->userLevel;
       }
   
       function setUserId($userId) {
           $this->userId = $userId;
       }
   
       function setPassword($password) {
           $this->password = $password;
       }
   
       function setFirstName($firstName) {
           $this->firstName = $firstName;
       }
   
       function setSurname($surname) {
           $this->surname = $surname;
       }
   
       function setEmail($email) {
           $this->email = $email;
       }
   
       function setUserLevel($userLevel) {
           $this->userLevel = $userLevel;
       }
   
   }
   
   class UserDBServiceImpl extends DBService implements UserDBService {
   
       public function authenticate($Email, $Password) {
           global $database;
           $sql = "SELECT * FROM Users ";
           $sql .= "WHERE Email = '{$Email}' ";
           $sql .= "AND Password = '{$Password}' ";
           $sql .= "LIMIT 1";
           self::find_by_sql($sql);
           $result_array = self::find_by_sql($sql);
           return !empty($result_array) ? array_shift($result_array) : false;
       }
   
       public function find_by_sql($sql = "") {
   
           $result_set = $database->query($sql);
           $object_array = array();
           while ($row = $database->fetch_array($result_set)) {
               $object_array[] = self::instantiate($row);
           }
           return $object_array;
       }
   
       public function fetch_array($result_set) {
           return mysqli_fetch_array($result_set);
       }
   
       private function instantiate($row) {
           $object = new self;
           foreach ($row as $attribute => $value) {
               if ($object->has_attribute($attribute)) {
                   $object->$attribute = $value;
               }
           }
           return $object;
       }
   
       private function has_attribute($attribute) {
           $object_vars = get_object_vars($this);
           return array_key_exists($attribute, $object_vars);
       }
   
   }
   
   class DBService {
   
       private $database = null;
   
       private function init() {
           $this->database = ""; // Create connection to database
       }
   
       protected static function getInstance() {
           if ($database == null)
               init();
           return $database;
       }
   
   }
   
   interface UserDBService {
   
       public function authenticate($Email, $Password);
   
       public function find_by_sql($sql = "");
   
       public function fetch_array($result_set);
   
       function instantiate($row);
   
       function has_attribute($attribute);
   }
   

Answer 2

Use the standard property_exists() instead of has_attribute(). Also, use mysqli_fetch_assoc insted of mysqli_fetch_array to prevent getting mixed numeric/associative keys.