Support the ability to re-use packages from the Express/Connect ecosystem

[WonderPanda]

Taken from Discord conversation with @marcj

maybe we should just add support for the middleware API. make it easy to register a middleware for a route path and define its execution point in the http kernel (onAuth, onRequest, etc). the framework then has this information to debug execution of those middleware functions and an user can execute arbitrary plugins that would work in express as well, so that passport.js for example works almost the same with deepkit out of the box

[Rush]

How to use express middlewares today:

const expressMiddleware = async (
  request: HttpRequest, response: HttpResponse,
  middleware: (req: Request, res: Response, next: NextFunction) => void,
) => {
  const req = request as any as Request;
  const res = response as Response;
  return new Promise<void>((resolve, reject) => {
    middleware(req, res, (err: any) => {
      if (err) { return reject(err); }
      resolve();
    });
  });
};

const expressUse = async (
  request: HttpRequest, response: HttpResponse,
  ...middlewares: Array<(req: Request, res: Response, next: NextFunction) => void>
) => {
  for (const middleware of middlewares) {
    await expressMiddleware(request, response, middleware);
  }
  const req = request as any as Request;
  const res = response as Response;
  return { req, res };
};

and then use it as such (in this case with passport)

@injectable()
class AuthenticationListener {
  constructor(private logger: Logger) {
  }

  @eventDispatcher.listen(httpWorkflow.onAuth)
  async onAuth(event: typeof httpWorkflow.onAuth.event) {
    try {
      const { request, response } = event;
      const { req } = await expressUse(request, response,
        cookieParser,
        passport.initialize(),
        passport.authenticate(['jwt'], { session: true}),
      );

      if (req.user) {
        // request.store.user can then be accessed by parameter resolvers or http-scoped injection
        request.store.user = req.user;
      }
      if (event.route.groups.includes('auth') && !req.user) {
        event.accessDenied();
      }
    } catch (err) {
      this.logger.error('Error authenticating request', err);
      event.accessDenied();
    }
  }
}

[marcj]

This has been implemented, docs: https://deepkit.io/documentation/framework/http/middleware