Magento php add to cart with Custom price - php

Question

I have the following issue:
I make calculations via jQuery in the frontend and want to add a product to the cart with the price calculated in the frontend.
I already wrote a custom module with an AjaxController to achieve the adding to cart part, but I know struggle with setting the custom price.
My script looks like this:
$_prod = json_decode(Mage::app()->getRequest()->getPost('zapfsaeule_product'));
$id = 347; // there is only this one bundle product added to the cart viar this scipt, so a static id is enough.
$params = array(
'product' => $id,
'related_product' => null,
'bundle_option' => array(
6 => 17, // static options for testing purpouses
5 => 13), //
'qty' => 1 // static qty for testing as well
);
$cart = Mage::getSingleton('checkout/cart');
$product = new Mage_Catalog_Model_Product();
$product->load($id);
$cart->addProduct($product, $params);
$cart->save();
Mage::getSingleton('checkout/session')->setCartWasUpdated(true);
$this->getResponse()->setBody('true'); // setting response to true, because its an ajax request.
$this->getResponse()->setHeader('Content-type', 'text/plain');
That's the code for adding the product.
For setting the price I tried the approach as mentioned in this thread on stackexchange:
https://magento.stackexchange.com/questions/4318/dynamically-calculated-prices-save-before-add-to-cart
But it didn't work. I guess the event observed here doesn't occur in my case, because I wrote a custom script.
But then there still would be the problem, IF the observer approach would work, how would I pass the calculated price to the observer?
I hope you understand the problem and can help me solve it.
Thanks in advance!
Best regards,
Martin

Answer 1

Reading through Mage_Checkout_Model_Cart::addProduct(), there doesn't appear to be a way to set the item's price from the parameters. Instead, you'll need to add the product, then grab the resulting item, and set its price:
$cart->addProduct($product, $params)
->save();
// grab the corresponding item
$item = $cart->getQuote()->getItemByProduct($product);
// set its custom price
$item->setOriginalCustomPrice($customPrice)
->save();
Haven't had the time to try this out, but it should be the right idea. Make sure that you set the original_custom_price field (using setOriginalCustomPrice()), not one of the other prices. The other prices are recalculated during the totals process.

Answer 2

This comes pretty late, but I just stumbled upon this.
I got it to work like this:
$cart = Mage::getSingleton('checkout/cart');
$cart->addProduct($product, 1); // 1 = qty. Pass your qty and params.
$item = $cart->getQuote()->getItemByProduct($product);
$item->setCustomPrice(0); // or some other value
$item->setOriginalCustomPrice(0); // or some other value
$item->getProduct()->setIsSuperMode(true); // this is crucial
$cart->save();
Mage::getSingleton('checkout/session')->setCartWasUpdated(true);

Answer 3

If the params don't work, fetch the returned item from $cart->addProduct and change the price on the item before saving the cart.
$item = $cart->addProduct(...);
$item->setCustomPrice(...); {or whatever price attribute you like to set}
$cart->save();