Add exactly 1 product to cart programmatically in Magento

Question

Using Magento 1.8.1, on the checkout page, I'm trying to add a product to the cart in the code. Here is the code I'm using:

    $totals = Mage::getSingleton('checkout/cart')->getQuote()->getTotals();
    $subtotal = $totals["subtotal"]->getValue();
    $free_samples_prod_id = 1285;
    if ( $subtotal >= 50 ) {
        $this->addProduct($free_samples_prod_id, 1);
    }
    else{
        $cartHelper = Mage::helper('checkout/cart');
        $items = $cartHelper->getCart()->getItems();
        foreach ($items as $item) {
            if ($item->getProduct()->getId() == $free_samples_prod_id) {
                $itemId = $item->getItemId();
                $cartHelper->getCart()->removeItem($itemId)->save();
                break;
            }
        }
    }

The code is in: app\code\core\Mage\Checkout\Model\Cart.php under public function init()

The product does get added sucessfully, however, everytime somebody visits their cart page, the quantity increases by one. How can I modify that code so the quantity is always 1?

Thank you

Where are you inserting this code? Something is causing it to run each page load it seems, so you might want to address that. — Axel
I've added it under public function init() of app\code\core\Mage\Checkout\Model\Cart.php — farjam
Why are you introducing foreign code into core Models? You should be either extending the core through an extension, or overriding the files using the app/code/local/Mage folder. And putting code under the init method means it's going to run each time the cart is loaded. — Axel

PixieMedia PixieMedia · Accepted Answer · 2014-12-02T19:24:24

Axel makes a very good point, but to answer your immediate question, why not test for the product's presence before you add it

$cartHelper = Mage::helper('checkout/cart');
$items = $cartHelper->getCart()->getItems();
$subtotal = $totals["subtotal"]->getValue();
$free_samples_prod_id = 1285;

if ( $subtotal >= 50 ) {

    $alreadyAdded = false;
       foreach ($items as $item) {
           if($item->getId() == $free_samples_prod_id) { $alreadyAdded = true; break; }
       }
    if(!$alreadyAdded) { $this->addProduct($free_samples_prod_id, 1); }
}

Add exactly 1 product to cart programmatically in Magento

1 Answers