Type-safe request extensions

Is your feature request related to a problem? Please describe. Right now HttpRequest is can be assigned any property. Thanks to that you can pass custom properties down the stream as middleware-jwt does.

However, custom properties are of type any. I can’t see a way to make them type-safe. Am I missing something?

Describe the solution you’d like I’d like to pass custom properties in a type-safe manner as it is done with params, query, and body.

Describe alternatives you’ve considered I tried to extend the HttpRequest type and make my middleware return the extended version, but with no success.

Additional context

[JozefFlakus]

I have to analyze this topic deeper but the problem that you described is already known. For now r.use doesn’t infer types from middlewares but you can achieve the same thing using a similar approach:

const setUserProperties$ = r.pipe(
    r.matchPath('/:id'),
    r.matchType('PUT'),
    r.useEffect(req$ => req$.pipe(
      use(authenticate$),  // 👈
    )),
);

[sjanota]

I pressed “Comment” one test too early 😄.

I noticed that both use and useEffect return IxBuilder parametrized with HttpRequest as the last parameter. After I changed that to the types they are parametrized with it type-checks as expected. I’m talking of course about the declaration file in the npm bundle, not the source code.

Looks like RouteEffect could be defined as follows:

interface RouteEffect<I extends HttpRequest = HttpRequest, O extends HttpRequest = HttpRequest> {
  path: string;
  method: HttpMethod;
  effect: HttpEffect<O, HttpEffectResponse>;
  middleware?: HttpMiddlewareEffect<I, O>;
  meta?: RouteMeta;
}

And RouteEffectSpec should expose those types too so use and useEffect can use it. It’s doable, I can even prepare a PR if you find it feasible.

However, it would be great if one could achieve the same thing with combineRoutes. I think it’s impossible without changing the API, as RouteCombinerConfig accepts an array of middlewares.