Router and errors

Compose middleware and a handler

src/pages/api/status.ts

import { ExpressRoute } from '@astro-utils/express-endpoints';

const router = new ExpressRoute();

router.use((_req, res, next) => {
    res.set('Cache-Control', 'no-store');
    next();
});

export const GET = router.route((_req, res) => {
    res.json({ status: 'ready' });
});

next() allows the final handler to run. A middleware that sends a response should return without calling it.

ExpressRoute

Method	Behavior
use(middleware)	Appends middleware or another router and returns this router.
body(type)	Sets parsing to auto, json, multipart, urlencoded, or text.
validate(schemas)	Adds Zod Express validation to the next route.
route(...handlers)	Returns an Astro APIRoute.

Body parsing runs only for POST, PUT, and PATCH. In auto mode, the request Content-Type selects the parser.

Middleware stops unless it calls next(). A handler must write or end the response before the Astro route can complete.

Errors

ExpressError represents response lifecycle and header errors. ExpressBodyError extends it for body parsing failures.

Multipart parser failures are recorded on req.error. Other uncaught errors return their message using error.status when present, otherwise status 500.

Handle an application error

src/pages/api/double.ts

import { ExpressRoute } from '@astro-utils/express-endpoints';

const router = new ExpressRoute();

export const GET = router.route((req, res) => {
    const value = Number(req.query.value);
    if (req.query.value == null || !Number.isFinite(value)) {
        res.status(400).json({ error: 'Supply a numeric value query parameter.' });
        return;
    }
    res.json({ result: value * 2 });
});

Call /api/double?value=4 for {"result":8}, or omit value to see the explicit JSON error. Catch application failures where you can turn them into a useful response. Do not expose internal exception details to callers. ExpressError.code is not the same property as the router’s error.status fallback; explicitly set the response status when handling an error.