Free gift based on subtotal through coding? Which event dispatch?

Question

On every 25€ I wish to offer a product as a gift. With every 25 it increases another gift is added. So for instance, 102,50 will give 4 gifts.

I've allready got this working through cart.phtml. I know it actually should be done in code/local, but I'm having problems finding the proper dispatch event. There are events for adding a product, deleting etc. However, I need to make a definition on every action done in the cart.

I'm looking for an event which triggers as soon as the cart is called. This avoids a lot of hassle.

I've got the basic script working, I only need the direction to where and how I could insert this script.

Answer 1

You can also do it via the collecttotals hook. Not in front of a pc right now, so will update with example in a few hours. An example is in the config.xml of the core rules module.

The information as promised:

In your module config.xml, in the <global> tag you can place the following, which will allow you to call your model everytime magento does a call to ->collecttotals()

I actually use this in my own gifting module to effect gifting, based on the cart subtotal.

    <sales>
        <quote>
            <totals>
                <giftpromo>
                    <class>giftpromo/promo_gift</class>
                    <after>subtotal</after>
                    <before>tax_subtotal,shipping</before>
                </giftpromo>
            </totals>
        </quote>
    </sales>

This thus calls my model which is defined as such (added so you can see the class inheritance to make this work):

class ProxiBlue_GiftPromo_Model_Promo_Gift extends Mage_Sales_Model_Quote_Address_Total_Abstract
{
}

In this class you need a public method called collect, and to this core will pass the current shipping address object. From this you can get the current quote object.

My method is as such:

public function collect(Mage_Sales_Model_Quote_Address $address)
    {
        parent::collect($address);
        $quote = $address->getQuote();
        $store = Mage::app()->getStore($quote->getStoreId());
        if (!count($quote->getAllVisibleItems())) {
            return $this;
        }
        $this->_validator->init($store->getWebsiteId(), $quote->getCustomerGroupId(), $quote->getCouponCode());
        $this->_validator->processGiftRules($address);
        return $this;
    }

Obviously my method references other objects not part of the answer, but it would give you the general idea of how to use the collect totals.

For a core based example, see the class Mage_SalesRule_Model_Quote_Freeshipping

Have a peek in the core Sales module's config.xml, and you will see other examples of how to set the totals hook.

For completeness, here is that code:

<sales>
            <quote>
                <totals>
                    <freeshipping>
                        <class>salesrule/quote_freeshipping</class>
                        <after>subtotal</after>
                        <before>tax_subtotal,shipping</before>
                    </freeshipping>
                    <discount>
                        <class>salesrule/quote_discount</class>
                        <after>subtotal,shipping</after>
                        <before>grand_total</before>
                    </discount>
                </totals>
                <nominal_totals>
                    <nominal_discount>
                        <class>salesrule/quote_nominal_discount</class>
                        <sort_order>550</sort_order>
                    </nominal_discount>
                </nominal_totals>
            </quote>
        </sales>

Using the collect totals hook (right terminology?) you can easily run some custom code whenever the cart/quote changes totals.

Hope this helps.

Answer 2

What about sales_quote_save_before for checking and adding/removing

Answer 3

Ok, this is working perfect. I only need a way to remove the product, this doesn't work yet unfortunatelly, getting an error there

Invalid method Mage_Sales_Model_Quote_Item::removeItem

I know what this means, but I'm not sure what to call through the "Mage_Sales_Model_Quote_Item" to remove a product. If I get the base to work I wille expand this with and admin section, for now I'm happy if I got this working properly.

class Custom_FreeProduct_Model_Freeproductrow extends     Mage_Sales_Model_Quote_Address_Total_Abstract
{

public function collect(Mage_Sales_Model_Quote_Address $address)
{

    parent::collect($address); 

    $subtotal = $address->getSubtotalWithDiscount();
    $items = $address->getAllItems();

    $cartHelper = Mage::helper('checkout/cart');
    $freeProdCalc = floor($subtotal / 25);
    $freeProductExists = false;

    $cartItems = $cartHelper->getCart()->getItems(); 
    $cartItemsQty = count($cartItems);
    foreach ($cartItems as $item) 
    {
       $itemId = $item->getProductId();
       if ( $itemId == 10718 ) {
            $freeProductExists = true;
       }
    }

    if ( $subtotal < 25 ) 
    {
        foreach ( $items as $item ) {
            $itemProductId = $item->getProductId();
            $itemId = $item->getId();
            if ( $itemProductId == 10718 ) 
            {
                //$item->removeItem($itemId);
            }       
        }
    }
    elseif ( $freeProductExists ) 
    {
        foreach ( $items as $item ) {
            $itemId = $item->getProductId();
            if ( $itemId == 10718 ) 
            {
                $item->setQty($freeProdCalc);
            }       
        }
    } elseif ( $subtotal > 24.99 ) 
    {
        $_product = Mage::getModel('catalog/product')->load(10718);
        $cart = Mage::getModel('checkout/cart');
        $cart->init();
        $cart->addProduct($_product, array( 'product' => 10718, 'qty' => $freeProdCalc, 'options' => array( 542 => 2741 )));
        $cart->save();
    }

}

}

Answer 4

I would observe the event sales_quote_collect_totals_after which is called everytime the cart has changed and after shopping cart rules are applied and totals recalculated.

It receives the quote as parameter, so that you can retrieve the subtotal as follows:

$subTotal = $observer->getQuote()->getBaseSubTotal();

then add the free gift like this

$product = Mage::getModel('catalog/product')->load(FREE_PRODUCT_ID);
$item = $observer->getQuote()->addProduct($product, floor($subTotal / 25));
$item->setCustomPrice(0);

It's important that you set the following flag to prevent the totals to be collected again after this change which would cause an infinite loop:

$observer->getQuote()->setTotalsCollectedFlag(true);