[PHP/OOP] PDO inheritance

[dude]

hello

just started learning OOP yesterday and created my first class today:

<?php
class Database extends PDO
{

	private $host;
	private $user;
	private $password;
	private $name;
	private $cache_dir;
	public $cache_result = array();

	public function __construct($host, $user, $password, $name, $cache_dir)
	{
		$this->host = $host;
		$this->user = $user;
		$this->password = $password;
		$this->name = $name;
		$this->cache_dir = $cache_dir;
		
		try
		{
			parent::__construct('mysql:host='.$this->host.';dbname='.$this->name, $this->user, $this->password);
		}
		catch (Exception $e)
		{
			die('Error: ' . $e->getMessage());
		}
	}

	function cache($sql, $cache_time=0)
	{

		$digest = md5($sql);
		$cache_path = $this->cache_dir.'sql_'.$digest.'.txt';
			
		if(file_exists($cache_path)) // If the cache already exists...
		{
			$cache_date = filemtime($cache_path); // Gets cache time
			$now = time();
			$cache_age = $now - $cache_date;
			
			if($cache_age > $cache_time) // If the cache is outdated, we recreate it...
			{
				$q = parent::prepare($sql);
				$q->execute();
				$this->cache_result = $q->fetchAll();
				$f = serialize($this->cache_result); // Array to string
				file_put_contents($cache_path, $f);
			}
			else // sinon on le lit
			{
				$buff = file_get_contents($cache_path);
				$this->cache_result = unserialize($buff);
			}
		}
		else // else we create it
		{
			$q = parent::prepare($sql);
			$q->execute();
			$this->cache_result = $q->fetchAll();
			$f = serialize($this->cache_result); // Array to string
			file_put_contents($cache_path, $f);
		}
	}

	public function get_cache_result()
	{
		return $this->cache_result;
	}
	
	
}



$db = new Database('localhost', 'root', '', 'forum', 'cache/');
$db->cache('SELECT * FROM bbs_posts WHERE post_id = 501', 300);
$res = $db->get_cache_result();
echo '<pre>';
print_r($res);
echo '</pre>';
?>

so what do you think ? help me to improve it and learn more things

 

[litewarez]

well firstly why are you attempting to cache quires before there complete, make sure you cover every error possible so what your code should be doing is.

$db = new Database('localhost', 'root', '', 'forum', 'cache/');
$sql = 'SELECT * FROM bbs_posts WHERE post_id = 501';

$res = (!$db->is_cached($sql) ? $db->query($sql,true) : $db->get_cache_result($sql));

foreach($res as $id => $entity)
{
    //..
}

you will notice that there's a second param within query as this could be used to catch on success, so less user code.

but your concept is good, does exactly what you need it to do