Request & response

Handlers receive a Request and return a Response. The framework calls response.deliver (with optional CORS) after routing.

Request API

Function	Returns	Description
query(req, key)	String	Query parameter value
param(req, key)	String	Path param from :key segment (empty if no pattern)
header(req, name)	String	Request header (case-insensitive lookup via runtime)
body(req, max_len)	String	Read body up to max_len bytes (empty on failure)
body_result(req, max_len)	Result<String, int>	Body read with error code
context_value(req)	String	Middleware-parsed body stored on request
with_context(req, ctx)	Request	Attach context (used by middleware)
parse_json(req, max_len)	Result<String, int>	Read + validate JSON body

import lib.request
import lib.response

fn show(req: request.Request) -> response.Response {
    let q = request.query(req, "q");
    let id = request.param(req, "id");
    let auth = request.header(req, "Authorization");
    return response.json("{\"q\":\"" + q + "\",\"id\":\"" + id + "\"}");
}

After use_json middleware, prefer context_value(req) for the parsed JSON string instead of re-reading the body.

Response API

Function	Status	Content-Type
send(body)	200	inferred (plain)
send(status, body)	given	inferred (plain)
send_typed(status, ct, body)	given	explicit
json(body)	200	application/json; charset=utf-8
json(status, body)	given	application/json; charset=utf-8
send_status(status)	given	empty body
redirect(url)	302	Location header
redirect(status, url)	given	Location header

Error helpers

Function	Status
not_found(body)	404
bad_request(body)	400
payload_too_large(body)	413
unauthorized(body)	401
server_error(body)	500

fn create_item(req: request.Request) -> response.Response {
    let body = request.body(req, 65536);
    if len(body) == 0 {
        return response.bad_request("{\"error\":\"empty body\"}");
    }
    return response.json(201, "{\"ok\":true}");
}

Redirects

return response.redirect("/login");           // 302
return response.redirect(301, "/canonical"); // permanent

The runtime sets the Location header via http_reply_cors.

Barrel re-exports

When using import vws from vow_web_server, request/response helpers are also on the barrel:

let id = vws.param(req, "id");
return vws.json(201, "{\"ok\":true}");
return vws.redirect("/home");

Submodule imports (vow_web_server.request, vow_web_server.response) remain the typed option for handler signatures.

CORS on responses

use_cors(a, origin) wraps delivered responses with Access-Control-Allow-Origin. OPTIONS preflight returns 204 before middleware/route dispatch when CORS is enabled.

Note

Overloaded send / json / redirect rely on Vow compile-time overload resolution — same ergonomics as Express res.send.

Next

• Middleware — body parsing
• HTTP CRUD tutorial