Checkout only 1 item from magento cart

Question

I am trying to implement Buy Now feature and I find that if there are 2 items from before in cart, total of 3 items are shown in Checkout page when only 1 was expected.

All solutions that I have found in open source seem to add "buy now" product to cart first and then only checkout.

Is there a way where I can create another cart for same user ( guest / logged in ) so that this single item goes to that cart. I can subscribe to pre checkout event and then use that cart for fetching single item ?

Magento - 1.9

EDIT

I think there could be an approach where a cart full of items can be split into two orders , one for product that has been added using "buy now" and another for rest of items. Then, checking out buy now order would let checkout only 1 item. Is this correct approach since it seems checkout can not be decoupled from cart and also we can't create multiple carts !

Answer 1

The checkout uses the quote (cart) based on the quote id saved in the session. So to preserve the original cart but go to the checkout with another item, I would:

In the "buy now" action:

1. back up current quote id in session

   $quoteId = Mage::getSingleton('checkout/session')->getQuote()->getId();
   Mage::getSingleton('checkout/session')->setData('original_quote_id', $quoteId);
   

2. create new empty quote

   $quote = Mage::getModel('sales/quote')
   Mage::getSingleton('checkout/session')->replaceQuote($quote);
   Mage::getSingleton('checkout/cart')->setQuote($quote);
   

3. add product to cart based on request (similar to CartController::addAction())

   $request = $this->getRequest()->getParams();
   Mage::getSingleton('checkout/cart')->addProduct($request['product'], $request);
   

After checkout is complete (using an observer)

1. restore backed up quote

   $oldQuoteId = Mage::getSingleton('checkout/session')->getData('original_quote_id');
   if ($oldQuoteId) {
       $quote = Mage::getModel('sales/quote')->load($oldQuoteId);
       Mage::getSingleton('checkout/session')->replaceQuote($quote);
   }