PHP trying to use autoload function to find PDO class

This has been bugging me for some time now and I can't seem to make sense of it.

My phpinfo reports that PDO is installed and I can connect to my database on my index.php file. But when I try to open a PDO connection on a namespaced class, php is trying to use my autoload function to find PDO.php which won't work.

My class is as follows:

abstract class {

    protected $DB;

    public function __construct()
    {
        try {  
          $this->DB = new PDO("mysql:host=$host;port=$port;dbname=$dbname", $user, $pass);
        }  
        catch(PDOException $e) {  
            echo $e->getMessage();  
        }
    }
}

And the error is

Warning: require_once((...)/Model/PDO.php): failed to open stream: No such file or directory in /(...)/Autoloader.php

Fatal error: require_once(): Failed opening required 'vendor/Model/PDO.php' (include_path='.:/Applications/MAMP/bin/php/php5.4.4/lib/php') in /(...)/Autoloader.php

As far I as know the autoloader should be called because PHP PDO extension is installed (yes I'm completely sure).

My autoload is as follows:

spl_autoload_register('apiv2Autoload');

/**
 * Autoloader
 * 
 * @param string $classname name of class to load
 * 
 * @return boolean
 */
function apiv2Autoload($classname)
{
    if (false !== strpos($classname, '.')) {
        // this was a filename, don't bother
        exit;
    }

    if (preg_match('/[a-zA-Z]+Controller$/', $classname)) {
        include __DIR__ . '/../controllers/' . $classname . '.php';
        return true;
    } elseif (preg_match('/[a-zA-Z]+Mapper$/', $classname)) {
        include __DIR__ . '/../models/' . $classname . '.php';
        return true;
    } elseif (preg_match('/[a-zA-Z]+Model$/', $classname)) {
        include __DIR__ . '/../models/' . $classname . '.php';
        return true;
    } elseif (preg_match('/[a-zA-Z]+View$/', $classname)) {
        include __DIR__ . '/../views/' . $classname . '.php';
        return true;
    }
}

Any help please?

Its not really an autoload issue. You are attempting to call a class on the root namespace.

By the looks of it your are in some 'Model' namespace and calling PDO, you must remember that namespaces are relative by default.

What you want is to either call the the absolute path: