Question

I have the following PDO Initialization set in my constructor for a PDO wrapper:

public function __construct($engine, $host, $username, $password, $dbName)
{
    $this->host = $host;
    $this->dsn = $engine.':dbname='.$dbName.';host='.$host;
    $this->dbh = parent::__construct($this->dsn, $username, $password);
    $this->dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);      
}

My main problem is that when I set dbh to initialize as a parent in a constructor, it returns NULL.

and that creates a chain reaction.

Is there anything specific that I’m doing wrong?

Answer 1

You are mixing up wrapping a class and inheriting a class.

Either do this (wrapping):

class YourDB
{
    public function __construct($engine, $host, $username, $password, $dbName)
    {
        $this->host = $host;
        $this->dsn = $engine.':dbname='.$dbName.';host='.$host;
        // here we are wrapping a PDO instance;
        $this->dbh = new PDO($this->dsn, $username, $password);
        $this->dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);      
    }

    // possibly create proxy methods to the wrapped PDO object methods

}

Or (inheriting):

class YourDB
    extends PDO // extending PDO, and thus inheriting from it
{
    public function __construct($engine, $host, $username, $password, $dbName)
    {
        $this->host = $host;
        $this->dsn = $engine.':dbname='.$dbName.';host='.$host;
        // here we are calling the constructor of our inherited class
        parent::_construct($this->dsn, $username, $password);
        $this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);      
    }

    // possibly override inherited PDO methods

}