setCustomPrice is reset in checkout process

Question

I want to add a product to a cart and change its price to 0.

Currently I have :

$request = new Varien_Object([
    'qty' => 1,
]);
$cart->getQuote()
     ->addProductAdvanced(Mage::getModel('catalog/product')
     ->load($productId), $request)
     ->setCustomPrice(0)
     ->setOriginalCustomPrice(0);

That work, but in the DB, I have only the product, not the linked configurable (and I need it). So I try the same thing with the configurable :

$request = new Varien_Object([
    'qty' => 1,
    'super_attribute' => array(
        $sizeAttributeId => $sizeValue, 
        $priceAttributeId => 0,
    )
]);
$cart->getQuote()
     ->addProductAdvanced(Mage::getModel('catalog/product')
     ->load($configurableProductId), $request)
     ->setCustomPrice(0)
     ->setOriginalCustomPrice(0);

Now, that work too : when I go on the cart, I have my product with 0 in price (and if I valid the order, I have my configurable in DB). But then, if a go in the checkout process, my price is reset to the original price... Someone now why ? May be I did something bad ?

Answer 1

Finally I find a way (if womeone is interested) :

$request = new Varien_Object([
    'qty' => 1,
    'super_attribute' => array(
        $sizeAttributeId => $sizeValue, 
        $priceAttributeId => 0,
    )
]);
$newItem = $cart
    ->getQuote()
    ->addProductAdvanced(Mage::getModel('catalog/product')
    ->load($configurableProductId), $request)
    ->getParentItem();
$newItem->setCustomPrice(0)->setOriginalCustomPrice(0);

That works for me and no side effect for the moment :)