Magento failing when trying to save product inside event observer on frontend?

Question

I have a function that is tied to an event observer

One of the requirements is that when it loops through the order item data, if a certain product attribute is empty it issues a request to get specific data through a separate model (working fine).

the problem code basically boils down to this

foreach ($order->getAllItems() as $key => $item) {
    /** @var Tantor_Catalog_Model_Product $productData */
    $productData = $item->getProduct();
    $_item = Mage::getModel('catalog/product')->load($productData->getId());
    $_item->setNetsuiteItemIid('foo');
    $_item->save();
}

however Magento is throwing an exception of

2014-03-05T21:14:14+00:00 ERR (3):
exception 'Exception' with message 'Warning: Invalid argument supplied for foreach()  in /var/www/html/app/code/core/Mage/Eav/Model/Entity/Abstract.php on line 1180' in /var/www/html/app/code/core/Mage/Core/functions.php:245
Stack trace:
#0 /var/www/html/app/code/core/Mage/Eav/Model/Entity/Abstract.php(1180): mageCoreErrorHandler(2, 'Invalid argumen...', '/var/www/html/a...', 1180, Array)
#1 /var/www/html/app/code/core/Mage/Eav/Model/Entity/Abstract.php(1123): Mage_Eav_Model_Entity_Abstract->_collectSaveData(Object(Tantor_Catalog_Model_Product))
#2 /var/www/html/app/code/core/Mage/Core/Model/Abstract.php(318): Mage_Eav_Model_Entity_Abstract->save(Object(Tantor_Catalog_Model_Product))
#3 /var/www/html/app/code/local/Tantor/Netsuite/Model/Observer.php(218): Mage_Core_Model_Abstract->save()
#4 /var/www/html/app/code/core/Mage/Core/Model/App.php(1338): Tantor_Netsuite_Model_Observer->saveOrder(Object(Varien_Event_Observer))
#5 /var/www/html/app/code/core/Mage/Core/Model/App.php(1317): Mage_Core_Model_App->_callObserverMethod(Object(Tantor_Netsuite_Model_Observer), 'saveOrder', Object(Varien_Event_Observer))
#6 /var/www/html/app/Mage.php(447): Mage_Core_Model_App->dispatchEvent('sales_order_pla...', Array)
#7 /var/www/html/app/code/core/Mage/Sales/Model/Order.php(1096): Mage::dispatchEvent('sales_order_pla...', Array)
#8 [internal function]: Mage_Sales_Model_Order->place()
#9 /var/www/html/app/code/core/Mage/Core/Model/Resource/Transaction.php(105): call_user_func(Array)
#10 /var/www/html/app/code/core/Mage/Core/Model/Resource/Transaction.php(159): Mage_Core_Model_Resource_Transaction->_runCallbacks()
#11 /var/www/html/app/code/core/Mage/Sales/Model/Service/Quote.php(189): Mage_Core_Model_Resource_Transaction->save()
#12 /var/www/html/app/code/core/Mage/Sales/Model/Service/Quote.php(249): Mage_Sales_Model_Service_Quote->submitOrder()
#13 /var/www/html/app/code/core/Mage/Checkout/Model/Type/Onepage.php(774): Mage_Sales_Model_Service_Quote->submitAll()
#14 /var/www/html/app/code/core/Mage/Checkout/controllers/OnepageController.php(511): Mage_Checkout_Model_Type_Onepage->saveOrder()
#15 /var/www/html/app/code/core/Mage/Core/Controller/Varien/Action.php(419): Mage_Checkout_OnepageController->saveOrderAction()
#16 /var/www/html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch('saveOrder')
#17 /var/www/html/app/code/core/Mage/Core/Controller/Varien/Front.php(176): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#18 /var/www/html/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#19 /var/www/html/app/Mage.php(683): Mage_Core_Model_App->run(Array)
#20 /var/www/html/index.php(86): Mage::run('', 'store')
#21 {main}

Why would i be able to use identical code in a 3rd party script outside the magento observer just fine, but when I try to run it inside that observer, it fails with that random error message?

Answer 1

The problem is, that you are not allowed to save products from the frontend.

This is done through the fact, that when you load a product in frontend, the origData property is not filled:

public function setOrigData($key=null, $data=null)
{
    if (Mage::app()->getStore()->isAdmin()) {
        return parent::setOrigData($key, $data);
    }

    return $this;
}

So when you try to save the product, the error you describe is raised.

You can solve this problem either when you change the current store to admin, e.g. with the code from @magboy:

Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);

better using Mage_Core_Model_App_Emulation

And my prefered solution is to extend Mage_Catalog_Model_Product and replace the setOrigData method

public function setOrigData($key = null, $data = null)
{
    if (is_null($key)) {
        $this->_origData = $this->_data;
    } else {
        $this->_origData[$key] = $data;
    }
    return $this;
}

I'm NOT talking about a rewrite here! Only use your model on this one place to enable saving. Then you have the security-feature still active everywhere else.

Answer 2

Try adding this line of code:

Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);

I'm not sure why you have to do this now in the current version of Magento. Maybe someone else can explain?