Magento: limit product max quantity to 1 per order. quantity 2 = 2 orders

Question

Is it anyhow possible to limit specific products in Magento to a max quantity of one per order? This means the user can only order one product at a time. If he wants to orde

Answer 1

The below should fix your issue:

public function enforceSingleOrderLimit($observer){
     if (!$this->_helper->isModuleEnabled()) {
        return;
    }
    $cart = Mage::getModel('checkout/cart')->getQuote();
    if ($cart->getItemsCount() > 1) {

        Mage::getSingleton('checkout/session')->addError('limit only one product per order');
        Mage::app()->getFrontController()->getResponse()->setRedirect(Mage::getUrl('checkout/cart'));
        Mage::app()->getResponse()->sendResponse();
        exit;
    }
}