My suggestion would be to put an observer on the sales_quote_collect_totals_before
event which is fired in the Mage_Sales_Model_Quote::collectTotals
method before it starts the total collection process. Then from inside this observer method, iterate the quote items and change the tax class on the (already loaded) product object you can retrieve from the quote item.
After you set the information on the product object, whatever you do, DO NOT try and save it to the database. Having the tax class set as needed on the product object in memory will be good enough to have the collect totals logic found in Mage_Tax_Model_Sales_Total_Quote_Tax
pickup which tax class it should base it's calculations on. Saving the product (as you seem to be trying to do in your code sample above) will cause major performance issues, will create race conditions in the calculation process, and is simply not good practice.
The reason that the events you are trying to work with are not enabling you to accomplish what you are trying to accomplish is because they all come after the total calculation, a process which is only be run once prior to saving the quote.
Worth pointing out about the collect totals process is that once run, without doing extra work, you cannot call it again to have it re-calculate based on changes you've made to the quote items. See this tie-bit I've taken from the blog series a colleage of mine recently put together on the collect totals process:
Now that you understand what occurs during the totals collection
process, you may find it convenient or necessary to call it directly
yourself. Before you start feeling too confident with using
collectTotals for your own purposes, though, keep the following rule
in mind:
Products cannot be added to the quote after collectTotals is run!
. . . unless the quote addresses' item caches are cleared.
Nearly every total model's "collect" method relies on fetching the
quote items from the address and looping through them. The first time
getAllItems is run on a quote address, the item collection is actually
cached with a unique key, and it's this cached collection that is
returned on subsequent calls.
If you do happen to have an inkling for really diving into the depths of how the collect totals process works, you can check out the first of the four part series on total collection here for more in-depth reading: Unravelling Magento's collectTotals: Introduction
To summarize, you need to be catching an event which runs before the collect totals process (and before getAllItems is called on the quote addresses) so that changes you make to the items will be used by the total collectors. I've not verified that the suggested sales_quote_collect_totals_before
event runs before any calls to the getAllItems
on the quote address, but I'm almost certain that it will work for what you need. But if not, hopefully I've provided enough context for you to figure out which event you need to catch to make it work.
You can get the simple product details on the same event by placing the following code in your observer :
$main_product = $observer->getEvent()->getProduct();
$associated_product = $observer->getEvent()->getQuoteItem();
$productSku = $main_product ->getSku(); //for configurable product
$productQty = $main_product ->getQty(); //for configurable product
if($product->getTypeID() == 'configurable'){
//to get the id or sku of associated product use the following.
$simple_product_id = $quoteitem->getProduct()->getId();
$simple_product_sku = $quoteitem->getProduct()->getSku();
}
Hope this works for you.
Best Answer
You need to find the simple product in the cart that is associated to the configurable product and get the attribute from that one.
The simple cart item is linked through the configurable one through
$item->getParentItemId()
. So you should loop through all the cart items, not just visible ones until you find one that matches your needs.Here is a possible way of doing it.
What I described above can be used in the general case, when you need something from the simple product, but in your case is even more simple.
All you need is to find a product that is overweight. If you have one it means you cannot use
flatrate
.You shouldn't care if the product is configurable or not. You just need one item. So instead of looping through
getAllVisibleItems
you should loop throughgetAllItems