Magento relevant product when product is added to cart - magento

Question

I am programming an extension which adds relevant products to the cart once you add an item to the cart. Example if you are buying a pen I am going to add paper to the cart. Bundled packages are not an option since I need to match certain conditions. I tried the following:
I set up an event listener "sales_quote_item_collection_products_after_load" scan all the products in cart and add the relevant products. Sadly you have to reload the cart in order to make the products appear.
I used this code in, my event listener, to add products to cart:
// Get cart instance
$cart = Mage::getSingleton('checkout/cart');
$cart->init();
// Add a product (simple); id:12, qty: 3
$cart->addProduct(12, 3);
$cart->save()
The strange thing is that removing products using the cart helper works (without refreshing):
$cartHelper = Mage::helper('checkout/cart');
$items = $cartHelper->getCart()->getItems();
foreach ($items as $item) {
if ($item->getProduct()->getId() == $productId) {
$itemId = $item->getItemId();
$cartHelper->getCart()->removeItem($itemId)->save();
break;
}
}
Is there a way to tell Magento to "requote" or what would you recommend? I also thought of adding the product, at the add to cart listener. But in that case I will need to implement it as well on update and remove, so it will work correctly. Using sales_quote_item_collection_products_after_load after load seemed to be the best option, since I have everything in one place.

Answer 1

You need to change in your code
$product_model = Mage::getModel('catalog/product');
$product_id =35;
$my_product = $product_model->load($product_id);
$cart = Mage::getModel('checkout/cart');
$cart->init();
$cart->addProduct($my_product, array('qty' => 1));
$cart->save();
Mage::getSingleton('checkout/session')->setCartWasUpdated(true);