The Cart/PurchaseURL element provides a specially formatted link to Amazon. From your application or Web site, you must give your customers a way to access the purchase URL. Depending on the MergeCart parameter value of the cart, a customer can go through two different scenarios after activating the purchase URL:
Note:
The default value for MergeCart in the US locale is False. For non-US locales, MergeCart can only be True.
The MergeCart parameter is set by the CartCreate and CartModify operations.
When MergeCart is True the remote cart contents are merged with the customer's Amazon cart and the remote cart contents are deleted. In non-US locales, the value can only be True, so the parameter is ignored. In the US locale, however, the default value is False. So, to make the value True, the MergeCart value must be set in the request.
Once you hand off a customer to the Amazon Web site, the user logs in to their existing Amazon account (or creates a new account) and the contents of the shopping cart that you created are transferred to the customer's Amazon cart. If the customer has an existing Amazon cart, the remote cart contents merge with any items that are already in that customer's cart. If you are an Amazon Associate, you will receive Associate referral fees on items in the cart that were added while the customer was on your site, as well as any items that the customer adds within 24 hours of clicking through the purchase URL. You will not receive referral fees for items that were already in the Amazon cart before the customer accessed the purchase URL.
When the purchase URL is submitted, the cart contents are no longer accessible. The cart is empty, but will continue to exist for the life defined by Amazon (currently 90 days). We do not recommend using the cart after submitting it to Amazon for purchase.
MergeCart can only be False in the US locale. In the US locale, False, is the default value. When MergeCart is False and the PurchaseURL is submitted the customer is sent directly to the Order Pipeline and only the remote cart contents are available for purchase, In this case, the items are not deleted from the remote cart until the purchase is completed. Use the CartClear or CartModify operations to remove cart contents from a remote cart.