CODEWITHSUNDEEP
phpmysqlclasspdo
user1537415
user1537415

Reputation:

Unable to use PDO inside class

I've a simple class, User which requires database access. I also require database access in several other classes, so my class.user.php looks like this: 

include "config.php"

class User {

    public $db;

    public function __construct(PDO $db){
        $this->db = $db;
        global $db;
    }

    function LastLogin(){
        // global $db; // if I uncomment this, it works for this function. 
        $pdo = $db->prepare("SELECT last_login FROM users WHERE username = ?");
        $pdo->execute(array($username));
        while($r = $pdo->fetchObject()){
            echo $r->last_login;
        }
    }
}

Config.php looks like this: 

$dsn = "mysql:host=localhost;dbname=db;charset=utf8";
$opt = array(
    PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
);
$db = new PDO($dsn,'user','pass', $opt);

So let's say I have page called userdetails.php, and I want to know when the user has last logged in. 

$user = new User($db);
$user->LastLogin();

This results in a error message like this:

Notice: Undefined variable: db in /home/www/class.user.php on line 12 
Fatal error: Call to a member function prepare() on a non-object in/home/www/class.user.php on line 12

So I'm having problems with using pdo inside the class. It makes no sense to type "global $db" to every function, so what am I doing wrong?

Upvotes: 1

Views: 295

Answers (4)

RiggsFolly
RiggsFolly

Reputation: 94642

try this

include "config.php"

class User {

    public $db;

    public function __construct($db){
        $this->db = $db;
      }

    function LastLogin(){
        $pdo = $this->db->prepare("SELECT last_login FROM users WHERE username = ?");
        $pdo->execute(array($username));
        while($r = $pdo->fetchObject()){
            echo $r->last_login;
        }
    }
}

The global $db is definitely not required and is bad practice as it destroys the encapsulation of a class.

The type hint PDO in __construct(PDO $db) is also not actually legal as far as I know.

And while you have a property of $db and loaded it with the correct handle, to use it chnage this 

$pdo = $db->prepare("SELECT last_login FROM users WHERE username = ?");

To

$pdo = $this->db->prepare("SELECT last_login FROM users WHERE username = ?");

So you are using/addressing it correctly.

Upvotes: 1

fortune
fortune

Reputation: 3372

Remove global $db from your constructor.

Use $this->db instead of $db in function LastLogin

Upvotes: 1

Kevin Kopf
Kevin Kopf

Reputation: 14195

global $db is the problem. Loose it and it all should work.

Upvotes: 1

Darren
Darren

Reputation: 13128

As stated in the comments, remove the line:

global $db;

Also, you don't need to pass the PDO either.

And instead of trying to reference it as 

$db->prepare(....)

You want to reference it as:

$this->db->prepare(....)

since you're instantiating it as a variable accessible within the class.

Upvotes: 2

Related Questions