Changing currency of request via scripted rest api

[Wasd123]

We have a scripted rest api what is based on the incoming JSON message it raises a catalog item (request, request item and tasks). All works fine, except the price field in the request.

 While the amount is passed over correctly I can't seem to find a way to change the currency based on the incoming message. Is there a way to update the currency based on the JSON message either via the cart api or business rule?

[Tony Chatfield1]

Hi, unfortunately your post contains no details of how your transform is configured.
How are you populating the currency field?
The docs indicate 3 digit currency code 'space' value eg, EUR 1.234,56

Default currency values in import and export (servicenow.com)