問題描述
PHP PDO ‑ 無法序列化或反序列化 PDO 實例 (PHP PDO ‑ cannot serialize or unserialize PDO instances)
I need to pass a PDO connection into a cart class from a controller,
function __construct($connection)
{
$this‑>cart = new cart($connection);
}
but I think the problem is with serialize()
public function render_page()
{
if (!isset($_SESSION[SESSION_CART]))
{
$cart = $this‑>cart;
}
else
{
$cart = unserialize($_SESSION[SESSION_CART]);
}
$_SESSION[SESSION_CART] = serialize($cart);
}
I get this error,
Fatal error: Uncaught exception 'PDOException' with message 'You cannot serialize or unserialize PDO instances' in C:\wamp\www\store_2012_MVC\local\controllers\class_base_extended_cart.php:89 Stack trace: #0 [internal function]: PDO‑>__sleep() #1 C:\wamp\www\store_2012_MVC\local\controllers\class_base_extended_cart.php(89): serialize(Object(cart)) #2 C:\wamp\www\store_2012_MVC\local\controllers\class_factory.php(75): base_extended_cart‑>render_page() #3 C:\wamp\www\store_2012_MVC\index.php(69): factory‑>render() #4 {main} thrown in C:\wamp\www\store_2012_MVC\local\controllers\class_base_extended_cart.php on line 89
How can I fix this?
Or can I use something else instead of serialize()?
EDIT:
I tried it with __sleep and __wakeup magic methods but still get the same error,
class database_pdo
{
# database handler
protected $connection = null;
# make a connection
public function __construct($dsn,$username,$password)
{
try
{
$this‑>connection = new PDO($dsn, $username, $password, array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));
$this‑>connection‑>setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch (PDOException $e)
{
# call the get_error function
$this‑>get_error($e);
}
}
# don't forget to add getter method to get $this‑>connection, it's just a good practice.
public function get_connection()
{
return $this‑>connection;
}
public function __sleep()
{
return array('connection');
}
public function __wakeup()
{
$this‑>connection;
}
}
‑‑‑‑‑
參考解法
方法 1:
PDO objects contain active links to databases (which may have a transaction initiated or db session settings and variabiles).
You cannot serialize a PDO object because the above would get lost and cannot be re‑established automatically.
You should redesign your classes to access the current database link statically using a separate class (dedicated for holding db connections), instead of saving a reference in a member variable (I supose this is happening when you do new cart($connection))).
方法 2:
Take a look at the __sleep and __wakeup magic methods. http://us.php.net/manual/en/language.oop5.magic.php#object.sleep
They allow you to specify which properties get serialized and which get ignored. The issue there is that you'll need to regularly pass in an instance of your PDO object.
(by Run、oxygen、Chris Gutierrez)