OOP PHP error for non-object when trying to get user info from database [duplicate] - pdo

Question

This question already has answers here:
Call to a member function on a non-object [duplicate]
(8 answers)
Closed 10 years ago.
I'm trying to make oop class to get user info but i get this error
Fatal error: Call to a member function prepare() on a non-object in functions.php
user.php - >
include_once 'functions.php';
$user = new User();
echo $user->get_fullname(5);
functions.php ->
include_once 'database.php';
class User
{
public function connect()
{
$dbh = new DB_Class();
}
public function get_fullname($uid)
{
$getName = $dbh->prepare("SELECT EmailAddress FROM users WHERE UserID =:username");
$getName->bindParam(':username', $uid);
$getName->execute();
$rowName = $getName->fetch();
$email = $rowName['emailaddress'];
return $email;
}
}
database.php - >
class DB_Class
{
public function connect() {
try {
$dbh= new PDO("mysql:host=localhost;dbname=root",'users','password', array(
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"
));
} catch (PDOException $e) {
echo $e->getMessage();
}
$dbh->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_WARNING);
$dbh->setAttribute(PDO::ATTR_CASE,PDO::CASE_LOWER);
}
}
What i'm doing wrong :(

Answer 1

You never actually give access to the PDO instance $dbh to the things youre trying to use it in. It seems like youre using classes simple as groupings of functions but also expecting some magic to happen :-) This is how i would do it with your existingcode:
class DB_Class {
protected $dsn;
protected $user;
protected $password;
protected $connection;
public function __construct($dsn = null, $user = null, $password = null)
{
$this->dsn = $dsn;
$this->user = $user;
$this->password = $password;
}
public function connect()
{
if($this->connection) {
return $this->connection;
}
try {
$this->connection = new PDO($this->dsn,$this->user, $this->password,
array(
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"
));
$this->connection->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_WARNING);
$this->connection->setAttribute(PDO::ATTR_CASE,PDO::CASE_LOWER);
return $this->connection;
}
catch (PDOException $e) {
return false;
}
}
}
class User {
protected $db;
public function __construct(DB_Class $db = null)
{
$this->db = $db;
}
public function setDb(DB_Class $db)
{
$this->db = $db;
}
public function get_fullname($uid)
{
$stmt = $this->db->connect()->prepare("SELECT EmailAddress FROM users WHERE UserID =:username");
$stmt->execute(array(':username', $uid));
if($row = $getName->fetch()) {
return $row['emailaddress'];
} else {
return null;
}
}
}

Answer 2

The $dbh variable isn't being passed into the get_fullname function. You'd need to do something like:
public function connect()
{
$dbh = new DB_Class();
return $dbh;
}
public function get_fullname($uid)
{
$dbh = $this->connect();

Answer 3

you need to declare $dbh as property of User class and access it via $this identifier:
class User
{
protected $dbh;
public function connect()
{
$this->dbh = new DB_Class();
}
public function get_fullname($uid)
{
$getName =$this->dbh->prepare("SELECT EmailAddress FROM users WHERE UserID =:username");
$getName->bindParam(':username', $uid);
$getName->execute();
$rowName = $getName->fetch();
$email = $rowMail['emailaddress'];
return $email;
}
}

Answer 4

You are never actually assigning your class properties as a property, all you are doing when declaring the variables inside of your methods is putting them into the methods current scope and they are destroyed once the method finishes execution.
To properly set a property within a class you need to declare them using $this->varname and the same goes for accessing them.
You are also using an incorrect name for the classes construction, the constructor must be set to __construct not connect.
As you can see in the updated code the $dbh variable is now a property of the User class and can be called between it's methods.
User Class
class User
{
public function __construct()
{
$this->dbh = new DB_Class();
}
public function get_fullname($uid)
{
$getName = $this->dbh->getConnection()->prepare("SELECT EmailAddress FROM users WHERE UserID =:username");
$getName->bindParam(':username', $uid);
$getName->execute();
$rowName = $getName->fetch();
$email = $rowName['emailaddress'];
return $email;
}
}
Database Class
class DB_Class
{
public function __construct() {
try {
$this->dbh = new PDO("mysql:host=localhost;dbname=root",'users','password', array(
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"
));
} catch (PDOException $e) {
echo $e->getMessage();
}
$this->dbh->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_WARNING);
$this->dbh->setAttribute(PDO::ATTR_CASE,PDO::CASE_LOWER);
}
public function getConnection() {
return $this->dbh;
}
}
You will benefit greatly by using http://us2.php.net/manual/en/oop5.intro.php as a resource.