Express异步中间件

Question

As we know, Express is not very good in handling async functions, in particular for the error handling.

I did define an asyncMiddleware as follows:

const asyncMiddleware = fn => (req, res, next) => {
  Promise.resolve(fn(req, res, next)).catch(next);
};

And then:

router.get('/', asyncMiddleware(myRouteHandler))

Is there a way to properly rewrite the middleware in order to make it usable directly by the Express router?

 router.use(asyncMiddleware)

Answer 1

Koa supports promises natively, it's expected that Express 5 will do this as well.

Is there a way to properly rewrite the middleware in order to make it usable directly by the Express router?

There is no way. In order to do that, Express app and router ( express.Router and express.Route classes) methods that use middlewares and route handlers should be monkey-patched to do what asyncMiddleware does.

Otherwise promise-based middlewares should be manually wrapped with a helper like asyncMiddleware .