writeonce/docs/examples/web-app/main.wo

-- web-app — the storefront: writeonce-framework (via [deps]) + @table
-- persistence. Every handler is a class satisfying Handler; the auth gate is
-- a Middleware; the data layer is the language's own database — no ORM, no
-- separate process, one binary.
use env
use json
use framework
use framework/http
use framework/router

-- decode target for POST /products, encode shape for every product answer
typedef ProductView = { name: Text, price: Float, stock: Int }
typedef NewOrder    = { product: Text, qty: Int }

fn view_json(name: Text, price: Float, stock: Int) -> Text {
  return json.encode(ProductView { name: name, price: price, stock: stock });
}

class ListProducts {
  pad: Int
  fn handle(req: Req) -> Resp {
    let body = "[";
    let first = true;
    for p in from x in Product order by x.name select x {
      if first == false { body = body .. ","; }
      first = false;
      body = body .. view_json(p.name, p.price, p.stock);
    }
    return ok_json(body .. "]");
  }
}

class ShowProduct {
  pad: Int
  fn handle(req: Req) -> Resp {
    let name = req.params["name"];
    if name == nil { return bad_request("no name"); }
    let hits = from p in Product where p.name == name take 1 select p;
    if len(hits) == 0 { return not_found(); }
    let p = hits[0];
    return ok_json(view_json(p.name, p.price, p.stock));
  }
}

-- Accepts THREE bodies: multipart/form-data (curl -F), a form post
-- (application/x-www-form-urlencoded), and JSON — same insert either way.
fn create_product(name: Text, price: Float, stock: Int) -> Resp {
  let made = try insert Product { name: name, price: price, stock: stock }
             catch (e) nil;
  if made == nil { return conflict("product name already exists"); }
  return created_json(view_json(name, price, stock));
}

class CreateProduct {
  pad: Int
  fn handle(req: Req) -> Resp {
    if media_type(req) == "multipart/form-data" {
      let ps = multipart_parts(req);
      if ps == nil { return bad_request("unreadable multipart body"); }
      let name = part_named(ps, "name");
      if name == nil { return bad_request("multipart needs name, price, stock"); }
      let pstr = part_named(ps, "price");
      if pstr == nil { return bad_request("multipart needs name, price, stock"); }
      let sstr = part_named(ps, "stock");
      if sstr == nil { return bad_request("multipart needs name, price, stock"); }
      -- parse_float answers NaN for unparseable input rather than a ?Float:
      -- "not a number" is already a Float value, and NaN != NaN is the test
      let price = parse_float(pstr);
      if price != price { return bad_request("price must be a number"); }
      let stock = parse_int(sstr);
      if stock == nil { return bad_request("stock must be a number"); }
      return create_product(name, price, stock);
    }
    if media_type(req) == "application/x-www-form-urlencoded" {
      let f = form_values(req);
      if f == nil { return bad_request("unreadable form body"); }
      let name = f["name"];
      if name == nil { return bad_request("form needs name, price, stock"); }
      let ps = f["price"];
      if ps == nil { return bad_request("form needs name, price, stock"); }
      let ss = f["stock"];
      if ss == nil { return bad_request("form needs name, price, stock"); }
      let price = parse_float(ps);
      if price != price { return bad_request("price must be a number"); }
      let stock = parse_int(ss);
      if stock == nil { return bad_request("stock must be a number"); }
      return create_product(name, price, stock);
    }
    let v = json.decode(req.body) as ProductView;
    if v == nil { return bad_request("body must be {name, price, stock}"); }
    return create_product(v.name, v.price, v.stock);
  }
}

class CreateOrder {
  pad: Int
  fn handle(req: Req) -> Resp {
    let v = json.decode(req.body) as NewOrder;
    if v == nil { return bad_request("body must be {product, qty}"); }
    if v.qty < 1 { return bad_request("qty must be positive"); }
    let hits = from p in Product where p.name == v.product take 1 select p;
    if len(hits) == 0 { return not_found(); }
    insert Order { product: hits[0], qty: v.qty };
    return created_json("{\"ok\":true}");
  }
}

class DeleteProduct {
  pad: Int
  fn handle(req: Req) -> Resp {
    let name = req.params["name"];
    if name == nil { return bad_request("no name"); }
    let hits = from p in Product where p.name == name take 1 select p;
    if len(hits) == 0 { return not_found(); }
    let gone = try delete hits[0] catch (e) nil;
    if gone == nil { return conflict("orders still reference this product"); }
    return ok_json("{\"deleted\":true}");
  }
}

fn main(args: multi Text) -> Int {
  if len(args) < 1 {
    print_err("usage: web-app <port>   (WA_TOKEN and WO_DATA must be set)");
    return 2;
  }
  let port = parse_int(args[0]);
  if port == nil {
    print_err("web-app: <port> must be a number");
    return 2;
  }
  let token = env.get("WA_TOKEN");
  if token == nil {
    print_err("web-app: WA_TOKEN is required (the auth middleware's bearer token)");
    return 2;
  }

  let app = App { middleware: [], routes: [] };
  -- the framework's Bearer mechanism: constant-time compare, principal
  -- attached to req.principal for handlers that want "who is this"
  app.use_mw(Mw { m: BearerAuth { token: token, principal: "api" } });
  app.get("/products",             ListProducts { pad: 0 });
  app.get("/products/:name",       ShowProduct { pad: 0 });
  app.post("/products",            CreateProduct { pad: 0 });
  app.post("/orders",              CreateOrder { pad: 0 });
  app.delete_("/products/:name",   DeleteProduct { pad: 0 });
  return app.serve("127.0.0.1", port);
}