add product to cart and change price and weight

Question

I need a module that when you add product to cart check two conditions and if they are correct will change the price for the product in the basket.

I need do something like this: - when product is added to the cart - get Qty and custom_attribute of product - if qty<0 and cutom_attribute value for product is >0 change of product price in cart (the changed price should be use in transactional emails, order view, on the invoice etc.)

I try use checkout_product_add_after, but I cannot get product attribute and check condition. How to get custom product attribute in this event?

Maybe should I use another event?

Answer 1

Try adding an observer for event event 'sales_quote_add_item':

<events>
    <sales_quote_add_item>
        <observers>
            <priceupdate_observer>
                <type>singleton</type>
                <class>mymodule/observer</class>
                <method>updatePrice</method>
            </priceupdate_observer>
        </observers>
    </sales_quote_add_item>
</events>

In your observer :

public function updatePrice($observer) {
    $event = $observer->getEvent();
    $quote_item = $event->getQuoteItem();

    $product = $quote_item->getProduct(); //You may need to load the product module or add the attribute to flat table
    $new_price = <insert logic>
    $quote_item->setOriginalCustomPrice($new_price);
    $quote_item->setWeight($newWeight);
    $quote_item->save();
}

See https://stackoverflow.com/questions/9721583/changing-the-price-in-quote-while-adding-product-to-cart-magento

Answer 2

I have the same need, that is to say change price as customer is adding the product to his cart. As I'm not accustom to things like $variable->getId() ... I use common PDO queries. I use this event with an observer : checkout_cart_add_product_complete I manage to get the cart, change the price, BUT it is impossible to update table sales_flat_quote_item ! I use this PDO query :

$connexion->exec("update sales_flat_quote_item set price='".$prixHT."', base_price=".$prixHT.", row_total=".$prixHT.", base_row_total=".$prixHT.", tax_amount=".$prixHT*0.2.", base_tax_amount=".$prixHT*0.2.", original_custom_price='".$prixTTC."', price_incl_tax='".$prixTTC."' base_price_incl_tax=".$prixTTC.", row_total_incl_tax='".$prixTTC."', base_row_total_incl_tax='".$prixTTC."' where item_id='".$ligne['item_id']."'");

NO CHANGE into sales_flat_quote_item . If I write the query directly into phpmyadmin, it works ! Why doesn't it work through the observer ? thank you for comments :)