Export the type of what is returned by AsyncRouter

[henrikra]

I have situation like this:

// fileA.ts
const router = RestypedRouter<MyAPI>(app);
configureRouter(router);

// fileB.ts
function configureRouter(router: any) { // <-- What type here
  // do stuff with router
}

As you can see from the code I am passing RestypedRouter as parameter to a function because I am doing stuff with it inside the function. But the problem is that I can't get the type for the router.

When I look generated index.d.ts file inside node_modules/restyped-express-async I will see definition like this

import * as express from 'express-serve-static-core';
import { RestypedBase, RestypedRoute } from 'restyped';
export interface TypedRequest<T extends RestypedRoute> extends express.Request {
    body: T['body'];
    params: T['params'];
    query: T['query'];
}
export default function AsyncRouter<APIDef extends RestypedBase>(app: express.Express | express.Router): {
    route: <Path extends keyof APIDef, Method extends "GET" | "POST" | "PUT" | "PATCH" | "HEAD" | "DELETE" | "OPTIONS">(path: Path, method: Method, handler: (req: TypedRequest<APIDef[Path][Method]>, res: express.Response) => Promise<APIDef[Path][Method]["response"]>) => void;
    use: any;
    get: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["GET"]>, res: express.Response) => Promise<APIDef[Path]["GET"]["response"]>) => void;
    post: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["POST"]>, res: express.Response) => Promise<APIDef[Path]["POST"]["response"]>) => void;
    put: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["PUT"]>, res: express.Response) => Promise<APIDef[Path]["PUT"]["response"]>) => void;
    delete: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["DELETE"]>, res: express.Response) => Promise<APIDef[Path]["DELETE"]["response"]>) => void;
    patch: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["PATCH"]>, res: express.Response) => Promise<APIDef[Path]["PATCH"]["response"]>) => void;
    options: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["OPTIONS"]>, res: express.Response) => Promise<APIDef[Path]["OPTIONS"]["response"]>) => void;
    head: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["HEAD"]>, res: express.Response) => Promise<APIDef[Path]["HEAD"]["response"]>) => void;
};

As you can see the return type of AsyncRouter is NOT exported.

🍏 Solution
Export return type as type. Add something like this to the types

export interface InternalRouter<APIDef extends RestypedBase> {
  route: <Path extends keyof APIDef, Method extends "GET" | "POST" | "PUT" | "PATCH" | "HEAD" | "DELETE" | "OPTIONS">(path: Path, method: Method, handler: (req: TypedRequest<APIDef[Path][Method]>, res: express.Response) => Promise<APIDef[Path][Method]["response"]>) => void;
  use: any;
  get: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["GET"]>, res: express.Response) => Promise<APIDef[Path]["GET"]["response"]>) => void;
  post: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["POST"]>, res: express.Response) => Promise<APIDef[Path]["POST"]["response"]>) => void;
  put: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["PUT"]>, res: express.Response) => Promise<APIDef[Path]["PUT"]["response"]>) => void;
  delete: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["DELETE"]>, res: express.Response) => Promise<APIDef[Path]["DELETE"]["response"]>) => void;
  patch: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["PATCH"]>, res: express.Response) => Promise<APIDef[Path]["PATCH"]["response"]>) => void;
  options: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["OPTIONS"]>, res: express.Response) => Promise<APIDef[Path]["OPTIONS"]["response"]>) => void;
  head: <Path extends keyof APIDef>(path: Path, handler: (req: TypedRequest<APIDef[Path]["HEAD"]>, res: express.Response) => Promise<APIDef[Path]["HEAD"]["response"]>) => void;
}

⚠️ Workaround:
My current workaround is just to copy paste the code above to my own source code. But this is not maintainable because if the type changes in Restyped library I have change my local source code too which is not idea.

👑 Please tell me if you have any questions and tell me if this is clear for you 👍

[ianmartorell]

Hey, I know it's been two years but if you're still interested in this, I forked this package to ianmartorell/restyped-express and I also want to use the function type in my code, but I'm not sure what's the best way to go about adding it. Any help would be appreciated.