Magento New Cart Attribute

Question

Hi well the problem I am facing seemed to be very simple at first but turned into a real nightmare now.

I was asked to add an attribute (namely point) to all the products (which was done pretty simple using the admin panel) and have its total as a cart attribute which rules can be set upon!?

I am quite positive that cart attributes are defined in:

class Mage_SalesRule_Model_Rule_Condition_Address extends Mage_Rule_Model_Condition_Abstract
{
public function loadAttributeOptions()
{
    $attributes = array(
        'base_subtotal' => Mage::helper('salesrule')->__('Subtotal'),
        'total_qty' => Mage::helper('salesrule')->__('Total Items Quantity'),
        'weight' => Mage::helper('salesrule')->__('Total Weight'),
        'payment_method' => Mage::helper('salesrule')->__('Payment Method'),
        'shipping_method' => Mage::helper('salesrule')->__('Shipping Method'),
        'postcode' => Mage::helper('salesrule')->__('Shipping Postcode'),
        'region' => Mage::helper('salesrule')->__('Shipping Region'),
        'region_id' => Mage::helper('salesrule')->__('Shipping State/Province'),
        'country_id' => Mage::helper('salesrule')->__('Shipping Country'),
    );

    $this->setAttributeOption($attributes);

    return $this;
}
<...>

So if I overwrite this model and add an item to that array I will get the attribute shown in rule definition admin panel. It seems that all these attributes has a matching column in sales_flat_quote_address table except for total_qty and payment_method!

Now the problem is what should I do to have my new attribute be calculated and evaluated in rules processing? should I add a column to this table and update its value upon cart changes?

Any insight on how to do this would be of great value thanks.

Answer 1

I finally managed to accomplish the task and just for future reference I explain the procedure here.

The class mentioned in the question (ie: Mage_SalesRule_Model_Rule_Condition_Address) is the key to the problem. I had to rewrite it and for some odd reason I couldn't get what I needed by extending it so my class extended its parent class (ie: Mage_Rule_Model_Condition_Abstract).

As I said I added my attribute to $attributes like this:

'net_score' => Mage::helper('mymodule')->__('Net Score')

I also modified getInputType() method and declared my attribute as numeric

now what does the trick is the validate() method:

public function validate(Varien_Object $object)
{
    $address = $object;
    if (!$address instanceof Mage_Sales_Model_Quote_Address) {
        if ($object->getQuote()->isVirtual()) {
            $address = $object->getQuote()->getBillingAddress();
        }
        else {
            $address = $object->getQuote()->getShippingAddress();
        }
    }

    if ('payment_method' == $this->getAttribute() && ! $address->hasPaymentMethod()) {
        $address->setPaymentMethod($object->getQuote()->getPayment()->getMethod());
    }

    return parent::validate($address);
}

as you can see it prepares an instance of Mage_Sales_Model_Quote_Address and sends it to its parent validate method. you can see that this object ($address) does not have payment_method by default so this method creates one and assigns it to it. So I did the same, simply I added the following code before the return:

if ('net_score' == $this->getAttribute() && ! $address->hasNetScore()) {
    $address->setNetScore( /*the logic for retrieving the value*/);
}

and now I can set rules upon this attribute.

Hope that these information saves somebody's time in the future.