I can't believe it, I really can't!
I'm writing a shopping cart for a website. One of the features required is to give the user an X amount discount off their next order when they buy a specific product. So let's say the user has a £20 discount on their next order, how does PayPal let me apply that? Simple answer, it doesn't!
You can't send a cart line with a negative price "Discount for 20 GBP", nor can you send a cart line with a positive price but a negative quantity (that was desperation). The way to do this apparently is to send a cart total. YES! By sending the entire order aggregated into a single order line. NOOOOOOO!!!!!!
So PayPal wants my user to order £100 of goods, click Check-out, and then be presented with "Total for your order £100 (£20 discount)", that's it? In my opinion, that's not very good. In fact, considering PayPal is probably the largest Internet payment organisation in the world I consider this to be atrocious!
Oh well, back to it...