Situation: I have this single product cart as rules on my cart page. What I did was I detect the other product being added by the user and display it on the top of the cart. See this photo: Second Item Added Notification

I want that when you click the continue button the Product on the Cart will be Empty and Replace by the Product Listed on the Notification. Can a link like /checkout/cart//?id= do that? If not what would be the possible thing to do?
Note: This is on the Shopping Cart Page.

2 Answers 2


You will need to go a little fancy for this. Extend the cart controller in your module and add some function, lets say it singlecartAction. It will look something like this :

public function singlecartAction() {
    $cart   = $this->_getCart();
    $params = $this->getRequest()->getParams();


    try {
        if (isset($params['qty'])) {
            $filter = new Zend_Filter_LocalizedToNormalized(
                array('locale' => Mage::app()->getLocale()->getLocaleCode())
            $params['qty'] = $filter->filter($params['qty']);

        $product = $this->_initProduct();
        $related = $this->getRequest()->getParam('related_product');

        if (!$product) {

        $cart->addProduct($product, $params);
        if (!empty($related)) {
            $cart->addProductsByIds(explode(',', $related));



            array('product' => $product, 'request' => $this->getRequest(), 'response' => $this->getResponse())

        if (!$this->_getSession()->getNoCartRedirect(true)) {
            if (!$cart->getQuote()->getHasError()) {
                $message = $this->__('%s was added to your shopping cart.', Mage::helper('core')->escapeHtml($product->getName()));
    } catch (Mage_Core_Exception $e) {
        if ($this->_getSession()->getUseNotice(true)) {
        } else {
            $messages = array_unique(explode("\n", $e->getMessage()));
            foreach ($messages as $message) {

        $url = $this->_getSession()->getRedirectUrl(true);
        if ($url) {
        } else {
    } catch (Exception $e) {
        $this->_getSession()->addException($e, $this->__('Cannot add the item to shopping cart.'));

Basically, I just combined functions of emptying the cart and adding product to the cart. You can wrap some try-catch around it and remove some extra code if you want.

  • can I call the function via link? if yes what would be the link?
    – Alen
    Nov 26, 2015 at 7:56
  • I guess it will be /checkout/cart/singlecart... am I right @Prateek ?
    – Alen
    Nov 26, 2015 at 8:02
  • I did add the code and what I get was an empty cart only.
    – Alen
    Nov 26, 2015 at 8:11
  • I did edit it @Prateek and the code works great except for the Success Message is not on the top most.
    – Alen
    Nov 26, 2015 at 8:25
  • It's based on default cart controller. Success message is being added to the session which will be displayed along with any other session messages on next page load. Can you elaborate a little what exactly is the issue you are facing with this ?
    – Prateek
    Nov 26, 2015 at 8:59

That's easy
Use below code in Product View Page just after $_product is defined.

To Empty the Cart


Add the Product Via Link

$_formKey= Mage::getSingleton('core/session')->getFormKey();     
$_productAddToCartLink= Mage::getUrl('checkout/cart/add',array('product'=>$_product->getId(), 'form_key'=> $_formKey));

<a href="<?php echo $_productAddToCartLink?>">Product Add To Cart Link</a>
  • /app/design/frontend/base/default/template/catalog/product/view.phtml Copy this file to your theme & put after $_product is defined. The link would be display on each product view page. Nov 26, 2015 at 7:22
  • How to trigger the cart to be empty first before adding the product?
    – Alen
    Nov 26, 2015 at 7:22
  • This must happen on the Shopping Cart Page not on the Product Page.
    – Alen
    Nov 26, 2015 at 7:30
  • When a new product will be added to cart. Cart will be empty automatically. Nov 26, 2015 at 7:31
  • That shouldn't be happening.
    – Alen
    Nov 26, 2015 at 7:49

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