Update cart Price before order placing

Question

I am having an API that give me price of metals and I want to use that price just before placing an order and re calculate the cart price before order has been placed.

In order to do that I created an observer. Here is the code for config file:

<?xml version="1.0" encoding="UTF-8"?>
<config>
<modules>
    <CustomPriceUpdate_Checkout>
        <version>0.0.1</version>
    </CustomPriceUpdate_Checkout>
</modules>
<global>
    <models>
        <myCustomPriceUpdate_Checkout>
            <class>CustomPriceUpdate_Checkout_Model</class>
        </myCustomPriceUpdate_Checkout>
    </models>
    <events>
        <sales_order_place_before>
            <observers>
                <modify_product_price>
                    <type>singleton</type>
                    <class>myCustomPriceUpdate_Checkout/observer</class>
                    <method>update_price</method>
                </modify_product_price>
            </observers>
        </sales_order_place_before>
    </events>
</global>
</config>

Observer.php:

<?php
class CustomPriceUpdate_Checkout_Model_Observer{
  public function update_price($observer){
    $client = new SoapClient('http://domain.com/index.php/api/v2_soap/?wsdl');
    $session = $client->login('username', 'key');  
    $quote = $observer->getQuote(); 
    foreach ($quote->getAllItems() as $item) {
        $product = $item->getProduct();//if you need it
        $product_id = $product->getId();
        $price = $product->getPrice();
        $discountprice = 23;
        $newPrice = ($price)+($discountprice);
        $product->setPrice($newPrice);
        $result = $client->catalogProductUpdate($session, $product_id, array(
                        'price' => $newPrice,
                    ),'brisbanebullion');
        Mage::log($product_id, null, "order.log", true);
    }
  }
}

I am using catalogProductUpdate API to update the price. The above code is only updating the price of Product, but its not updating the cart prices.

If I use the trigger "checkout_cart_save_before", then its changing price in both cart and catalog.

Can anyone please suggest me, which trigger I should use to update cart price just when user click place order button on checkout page.

Answer 1

You can use sales_order_place_before Event

resides in app/code/core/Mage/Sales/Model/Order.php place() Function

$order = $observer->getEvent()->getOrder();
$quote = $order->getQuote();
$quoteid=$quote->getId();
if($quoteid) {
    foreach($quote->getAllItems() as $item){
        $item->setCustomPrice(<YOUR PRICE>);
        $item->setOriginalCustomPrice(<YOUR PRICE>);
    }
}