Magento Bundle Products: Use Tier Prices of Simple Products

A Magento-Bug, that circulates in the Magento forums on and StackOverflow for some years, is that tier prices do not work properly together with bundle products. Over time there was some improvement but as for today (Magento CE 1.9) the following still does not work:

• Associated products with tier prices and qty > 1 in the bundle
• “Price as configured” display on bundle products with tier prices

There are some suggestions found on the web but more questions than answers, so I created a (hopefully) complete solution without core hacks and with only minimally invasive class rewrites. Until Magento gets it solved itself, you can use this module to enable bundles with tier prices:

SGH_BundleTierPrices (tested in Magento CE 1.8 and Magento CE 1.9)

Which changes were made in detail and how, I will explain here:

Bugfixes

Price Calculation

The problem: in bundle options that have tier prices themselves the tier prices in the bundle are not applied correctly.

To blame is Mage_Bundle_Model_Product_Price::getSelectionFinalTotalPrice():

 if ($bundleProduct->getPriceType() == self::PRICE_TYPE_DYNAMIC) {
    $price = $selectionProduct->getFinalPrice($takeTierPrice ? $selectionQty : 1);
}

Here the configured selection quantity $selectionQty is used for tier price calculation but the quantity of the bundle itself is ignored. By the way, the parameter of getFinalPrice() is only used for tier price calculation, the method always returns a unit price.

The corrected line looks as follows:

if ($bundleProduct->getPriceType() == self::PRICE_TYPE_DYNAMIC) {
    $price = $selectionProduct->getFinalPrice($takeTierPrice ? $selectionQty * max(1, $bundleQty) : 1);
}

I.e. if the quantity of the bundle $bundleQty is known, it will be multiplied.

To save the price correctly not only in the bundle but also in the selection itself, we have to trigger a recalculation of their final price as well because at least in some cases it is already calculcated (wrong) at this point. To achieve this, I added the following lines at the beginning of the method:

if ($takeTierPrice) {
    $selectionProduct->setFinalPrice(null);
}

Price Display in Frontend

The problem: The dynamic price display “Price as configured” does not work with tier prices.

To blame is Mage_Catalog_Model_Product_Type_Price::getTierPrice(), the method returns an array with tier price informations. The array keys are strings in the form {customer group}-{quantity}, generated in Mage_Catalog_Model_Product_Attribute_Backend_Groupprice_Abstract::preparePriceData(). When this array is printed as JSON for the dynamic price display it becomes an object, due to the string keys. But the JavaScript expects an array and tries to iterate over numeric indices.

Thus we have to achieve that getTierPrice() returns a numeric indexed array. I did not dare to touch the backend model, however the getTierPrice() method is not used anywhere, where the string keys would be relevant as far as I can see. So the rewrite looks as follows:

public function getTierPrice($qty = null, $product)
{
    $tierPrice = parent::getTierPrice($qty, $product);
    if (is_array($tierPrice)) {
        return array_values($tierPrice);
    }
    return $tierPrice;
}

Installation of the Extension

With Composer

    "require": {
        "sgh/bundletierprices": "dev-master",
    }
    "repositories": [
        {
            "type": "git",
            "url": "https://github.com/sgh-it/bundletierprices.git"
        }
    ]

Manually

1. Download Source Code
2. Copy app into the Magento installation directory (no files are overwritten, just added)