Update products when placing an order

Question

I tried to change the attribute value once we click on Place Order button present in checkout page :

config.xml :

<sales_convert_quote_to_order>
    <observers>
        <example_place_order>
            <class>Amasty_Example_Model_Observer</class>
            <method>PlaceOrder</method>
        </example_place_order>
    </observers>
</sales_convert_quote_to_order>

app/code/local/Amasty/Example/Model - Observer.php

public function PlaceOrder($observer)
{ 
    $product = $observer->getEvent()->getProduct();
    Mage::getSingleton('catalog/product_action')->updateAttributes(
        array($product->getId()),
        array('cart_status' => 0),
        $storeId = 0
    );
}

Result

Call to a member function getProduct() on a non-object in line: $product = $observer->getEvent()->getProduct();

Answer 1

Please try this ... it should set cart_status to 0 for all ordered products:

public function PlaceOrder(Varien_Event_Observer $observer)
{
    $quote = $observer->getQuote();
    $productIds = array();

    foreach ($quote->getItemsCollection() as $item) {
        $productIds[] = $item->getProductId();
    }

    Mage::getSingleton('catalog/product_action')->updateAttributes(
        $productIds,
        array('cart_status' => 0),
        $storeId = 0
    );
}

Answer 2

Try this:

public function PlaceOrder($observer) { 

     $product = $observer->getEvent()->getQuoteItem()->getProduct();
      Mage::getSingleton('catalog/product_action')->updateAttributes(
         array($product->getId()),
         array('cart_status' => 0),
         $storeId = 0
      );
}