Creating a coupon code for product with custom options

Question

I need to generate coupon codes for products with specific custom options. My sales rules have conditions for product SKU's and quantities. However, I don't know a good way to obtain the SKU for a product that has specific options. I tried the solution outlined on this site: http://inchoo.net/magento/magento-shopping-cart-promotion-rule-for-product-with-custom-options/

Unfortunately, generating SKU's in the format [main product SKU]-[first option SKU]-... is completely unreliable, since even the Magento test database has products with different SKU's in it. For example, an XL chealsea tee should have the SKU mtk000-XL, but the actual SKU is mtk000xl.

I understand that adding the product to the shopping cart with custom options might work, but I want to avoid using the cart for this purpose. I have access to the following data:

• The product object, which is loaded by its url using the method below
• The array which contains the custom options

Load item by URL:

public function getItemByUrl($url) {

    $itemUrl = str_replace(Mage::getBaseUrl(), "", $url);
    if (strpos($itemUrl, "/" === 0)) {
        $itemUrl = substr($itemUrl, 1);
    }

    $oRewrite = Mage::getModel('core/url_rewrite')
        ->setStoreId(Mage::app()->getStore()->getId())
        ->loadByRequestPath($itemUrl);

    if ($oRewrite == null) return null;

    $item_id = $oRewrite->getProductId();

    if ($item_id == null) return null;

    $product  = Mage::getModel('catalog/product')->load($item_id);

    return $product;

}

Array format:

attribute id => selected option id

For example, a medium khaki shirt has the following options array associated with it:

array(2) {
   [92]  => "28"
   [180] => "78"
}

To be clear, I only need a way to figure out the SKU that belongs to the specific product, for example, the medium khaki shirt. Once I have that, I have no problems with generating coupon codes.

Answer 1

Eventually, I've been able to come up with a method that does exactly what I need.

private function getSkuForOptions($product, $options) {

    $usedProducts = $product->getTypeInstance(true)->getUsedProducts(null, $product);

    $sku = -1;

    foreach ($usedProducts as $childProduct) {
        if (!$childProduct->isSaleable()) {
            continue;
        }

        $data = $childProduct->getData();
        $match = true;
        foreach ($options as $id => $value) {
            if (!isset($data[$id]) || $data[$id] !== $value) {
                $match = false;
            }
        }

        if ($match) {
            $sku = $childProduct->getSku();
            break;
        }

    }

    return $sku;

}

The $product parameter is the object returned by the method getItemByUrl, described in my original question. The parameter $options is an array in the following format:

attribute_code => value_id

For example, the red XL shirt is associated with the following options array:

array(2) {
  'color'  => 28
  'size'   => 78
}

My method looks for the saleable instances of the base product and tries to match their options to the ones supplied.

This idea came to me after many hours of reverse-engineering the magento core and reading this article: http://www.divisionlab.com/solvingmagento/magento-configurable-product-type-tutorial/