Bug with negative amounts in PayPal API

Question

I'm trying to use a negative amount with the PayPal Adaptive Payments API. To start with, this seems to work:

    'item' => [
      {
        'itemPrice' => '25.00',
        'name' => 'Cryptex - 16Gb USB Drive',
        'price' => '25',
        'itemCount' => 1
      },
      {
        'quantity' => 1,
        'name' => 'Special Discount',
        'price' => '-2.50'
      },
      {
        'itemPrice' => '5.00',
        'name' => 'Shipping',
        'price' => '5.00',
        'itemCount' => 1
      }
    ]

Here is an example of what I see after submitting this as JSON, and updating the items:

As you can see, the price IS correct ... yet there is no sign of the discounted amount? Its obviously taking it into account - otherwise the price would have been £30, not £27.50 (which is after the £2.50 discount)

What gives? Is this a bug in PayPals system?

FWIW, the emails are also broken - they don't show the discount amount at all.

UPDATE: I've opened a ticket with PayPal tech support, as I'm pretty sure this is a bug with their system, and not something that can be fixed this end :( Damn annoying!

UPDATE 2: Reply from PayPal:

PayPal Adaptive Payments do not support negative item values. Since you did not pass the <itemPrice> in your API Call, the system did not throw the following error message:

[errorId] => 580022
[domain] => PLATFORM
[subdomain] => Application
[severity] => Error
[category] => Application
[message] => Invalid request parameter: itemPrice cannot be negative

I can see that the following was submitted to PayPal:

<item>
<name>Special Discount</name>
<identifier></identifier>
<price>-2.50</price>
<itemPrice></itemPrice>
<itemCount></itemCount>
<any>[quantity: null]</any>
</item>

This object is basically incomplete and in order to apply discounts, you should apply them > onto the price for the main item and then submit it to PayPal.

I'm really not sure what they're suggestion I do? An example cart, would be:

Item 1 -  £10 
Item 2 -  £20 
Item 3 -  £50 
Item 4 -  £10 
Delivery - £5
Total   -  £95 

As an encouragement, we sometimes will offer coupons... so it could be "£10 off orders over £50". So in the above case above, it would drop the overall price to £85.

I'm really not sure what they are suggesting as an alternative?

Answer 1

Interesting. Normal payments don't have that restriction (I pass a negative amount item just like what you describe on a frequent basis).

What they're telling you to do is take the discount off another item. So your example cart with that discount would be

Item 1 -  £10 
Item 2 -  £20 
Item 3 -  £40 <-- Removed £10 discount
Item 4 -  £10 
Delivery - £5
Total   -  £85 <-- total reflects this