Hi @
georgio,
Here is the example of the request of adding a product to cart via REST API:
Code:
admin.php?target=RESTAPI&_key=test&_path=orderitem/0&_method=post&model[order][order_id]=8&model[object][product_id]=13&model[discountedSubtotal]=10.00
8 is the ID of the order/cart, 13 is the ID of the product, 10.00 is the price of a product, with which it will be added into the cart.
Hopefully, it will help.
Tony