prolog-point-of-sale/routes/products.pl

:- http_handler(root(api/products), products_page, []).

% POST /products
products_page(Request) :-
    member(method(post), Request), !,
    http_read_data(Request, Json, []),
    json_to_prolog(Json, product(Name, Price)),
    assert_product(Name, Price),
    reply_prolog(product(Name, Price)).

% GET /products
products_page(_Request) :-
    bagof(product(Name, Price), product(Name, Price), Products),
    reply_prolog(Products).