Question

I am currently adding products programatically to the cart, to create a ‘free sample’ aspect to my site.

Currently, all of these products are $0 and you can add a maximum of 15. Once you have 5 ‘free sample’ products in the cart, I need to add $20 to the subtotal.

I know I can get the grandtotal using:

Mage::getSingleton('checkout/cart')->getQuote()->getGrandTotal();

But how do I access the subtotal and also add $20 to it?

I’m guessing I’ll need to write an observer, as I’ll need to check when products are added/removed from the cart in order to either add the $20 or not.

Has anyone done this before or could point me in the right direction of how I could do this?

Many thanks

Thanks

Answer 1

I actually answered this question recently here is a basic idea of what needs to be done, let me know if you need more specific details:
Add an observer which looks for this 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>

The observer should have a method which does something like this:

public function updatePrice($observer) {
    $event = $observer->getEvent();
    $quote_item = $event->getQuoteItem();
    if(sample etc...) $new_price = <insert logic>
    $quote_item->setOriginalCustomPrice($new_price);
    $quote_item->save();
}