Incomplete PHP class when serializing object in sessions - php

Question

I'm working on a shopping cart (Cart model). One of its protected properties is "_items", which holds an array of Product objects. They (Products) all get stored in DB for populating the session (using ZF, Zend_Session_SaveHandler_DbTable() etc.).
public function addItem(Model_Product $product, $qty)
{
$qty = (int) $qty;
$pId = $product->getId();
if ($qty > 0) {
$this->_items[$pId] = array('product' => $product, 'qty' => $qty);
} else {
// if the quantity is zero (or less), remove item from stack
unset($this->_items[$pId]);
}
// add new info to session
$this->persist();
}
In the controller, I grab a Product obj from DB with the ProductMapper and provide it to "addItem()":
$product1 = $prodMapper->getProductByName('cap');
$this->_cart->addItem($product1, 2);
getProductByName() returns a new populated Model_Product object.
I usually get the
Please ensure that the class definition "Model_Product" of the object you are trying to operate on was loaded _before_ ...
error message, a session dump obviously shows
['__PHP_Incomplete_Class_Name'] => 'Model_Product'
I know about the "declaring the class before serializing it". My problem is this: how can I declare the Product class in addItem(), if it's injected (first param) in the first place? Wouldn't a new declaration (like new Model_Product()) overwrite the param (original object) in addItem()? Must I declare it in the Cart model again?
Besides, I'll surely get a Cannot redeclare class Model_Product if I... redeclare it in Cart.

Answer 1

In ZF's bootstrap, the session was started before autoloading.
/**
* Make XXX_* classes available
*/
protected function _initAutoloaders()
{
$loader = new Zend_Application_Module_Autoloader(array(
'namespace' => 'XXX',
'basePath' => APPLICATION_PATH
));
}
public function _initSession()
{
$config = $this->_config->custom->session;
/**
* For other settings, see the link below:
* http://framework.zend.com/manual/en/zend.session.global_session_management.html
*/
$sessionOptions = array(
'name' => $config->name,
'gc_maxlifetime' => $config->ttl,
'use_only_cookies' => $config->onlyCookies,
// 'strict' => true,
// 'path' => '/',
);
// store session info in DB
$sessDbConfig = array(
'name' => 'xxx_session',
'primary' => 'id',
'modifiedColumn' => 'modified',
'dataColumn' => 'data',
'lifetimeColumn' => 'lifetime'
);
Zend_Session::setOptions($sessionOptions);
Zend_Session::setSaveHandler(new Zend_Session_SaveHandler_DbTable($sessDbConfig));
Zend_Session::start();
}
When I was getting the errors I was talking about, the method declaration was the other way around: _initSession() was first, then _initAutoloaders() - and this was the exact order ZF was processing them.
I'll test some more, but this seems to work (and logical). Thanks for all your suggestions.