writeonce/docs/examples/shop/orders/controller.wo

-- orders/controller.wo — the buying flow: stock-checked order creation
-- (decrement + insert are each WAL-committed before they acknowledge)
-- and the orders list (ref navigation: o.product.name).
use serve/http
use layout
use time

pub class CreateOrder {
  fn handle(req: Req) -> Resp {
    let sku = req.params["sku"];
    if sku == nil {
      return html_error(404, "No such product", "The order names no product.");
    }
    let f = form_values(req);
    if f == nil {
      return html_error(400, "Bad order", "The form did not arrive form-encoded.");
    }
    let qraw = f["qty"];
    if qraw == nil {
      return html_error(400, "Bad order", "How many? The qty field is missing.");
    }
    let qty = parse_int(trim("${qraw}"));
    if qty == nil or qty < 1 {
      return html_error(400, "Bad order", "qty must be a positive number.");
    }
    let hits = from p in Product where p.sku == sku take 1 select p;
    if len(hits) == 0 {
      return html_error(404, "No such product", "Nothing is listed under that sku.");
    }
    let p = hits[0];
    if p.stock < qty {
      return html_error(409, "Not enough stock", "Only ${p.stock} left of ${p.name}.");
    }
    let total = p.price * float(qty);
    p.stock = p.stock - qty;
    insert Order { product: p, qty: qty, total: total, placed: time.now(), status: "placed" };
    let page = OrderOk { name: p.name, qty: qty, total: total };
    let shell = AppShell { title: "shop — order placed", content: page.render() };
    return ok_html(shell.render());
  }
}

pub class ListOrders {
  fn handle(req: Req) -> Resp {
    let rows: multi Component = [];
    for o in from x in Order select x {
      push(rows, OrderRow { name: o.product.name, qty: o.qty, total: o.total, status: o.status });
    }
    let page = OrdersPage { rows: rows };
    let shell = AppShell { title: "shop — orders", content: page.render() };
    return ok_html(shell.render());
  }
}