Getting error while using " return res.json({ }) "

[tanmayvaij]

using "express": "^4.21.0",
created this middleware for token verification

import { NextFunction, Request, Response } from "express";
import { JwtPayload, verify } from "jsonwebtoken";

declare global {
  namespace Express {
    interface Request {
      user: JwtPayload;
    }
  }
}

export const tokenVerifier = (
  req: Request,
  res: Response,
  next: NextFunction
) => {
  try {
    const authHeader = req.headers.authorization;

    if (!authHeader)
      return res.json({
        err: "authorization token was not provided",
        isSuccess: false,
      });

    const token = authHeader!.split(" ")[1];

    req.user = verify(
      token,
      process.env.FLEXIBASE_AUTH_SECRET_KEY!
    ) as JwtPayload;

    next();
  } catch (err) {
    return res.json({ isSucess: false, err });
  }
};

D:\Projects\flexibase-auth\node_modules\ts-node\src\index.ts:859
    return new TSError(diagnosticText, diagnosticCodes, diagnostics);
           ^
TSError: ⨯ Unable to compile TypeScript:
src/routers/auth.router.ts:13:38 - error TS2769: No overload matches this call.
  The last overload gave the following error.
    Argument of type '(req: Request, res: Response, next: NextFunction) => Response<any, Record<string, any>> | undefined' is not assignable to parameter of type 'RequestHandlerParams<ParamsDictionary, any, any, ParsedQs, Record<string, any>>'.
      Type '(req: Request, res: Response, next: NextFunction) => Response<any, Record<string, any>> | undefined' is not assignable to type 'RequestHandler<ParamsDictionary, any, any, ParsedQs, Record<string, any>>'.
        Type 'Response<any, Record<string, any>> | undefined' is not assignable to type 'void | Promise<void>'.
          Type 'Response<any, Record<string, any>>' is not assignable to type 'void | Promise<void>'.

13 authRouter.route("/verify-user").get(tokenVerifier, verifyUserController);
                                        ~~~~~~~~~~~~~

  node_modules/@types/express-serve-static-core/index.d.ts:203:5
    203     <
            ~
    204         P = ParamsDictionary,
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ...
    212         ...handlers: Array<RequestHandlerParams<P, ResBody, ReqBody, ReqQuery, LocalsObj>>
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    213     ): T;
        ~~~~~~~~~
    The last overload is declared here.

    at createTSError (D:\Projects\flexibase-auth\node_modules\ts-node\src\index.ts:859:12)
    at reportTSError (D:\Projects\flexibase-auth\node_modules\ts-node\src\index.ts:863:19)
    at getOutput (D:\Projects\flexibase-auth\node_modules\ts-node\src\index.ts:1077:36)
    at Object.compile (D:\Projects\flexibase-auth\node_modules\ts-node\src\index.ts:1433:41)
    at Module.m._compile (D:\Projects\flexibase-auth\node_modules\ts-node\src\index.ts:1617:30)
    at Module._extensions..js (node:internal/modules/cjs/loader:1435:10)
    at Object.require.extensions.<computed> [as .ts] (D:\Projects\flexibase-auth\node_modules\ts-node\src\index.ts:1621:12)
    at Module.load (node:internal/modules/cjs/loader:1207:32)
    at Function.Module._load (node:internal/modules/cjs/loader:1023:12)
    at Module.require (node:internal/modules/cjs/loader:1235:19) {
  diagnosticCodes: [ 2769 ]

i get this err while starting the server

[tanmayvaij]

the problem was in @types/[email protected] , when i used previous version the issue was solved

[brettearle]

EDIT: THIS COMMENT IRRELEVANT

Looking to lend a hand, what help do you want here? More info on the bug, updated types for 5.0, overload that allows res return?
Have only read this issue will dig in some tomorrow

[brettearle]

Q1: is it express intention to not call next and return out of a middleware? Doco is only representative of calling next(), to handle errors out of them it's handed to custom error handler
https://expressjs.com/en/guide/writing-middleware.html

EDIT: BELOW IRRELEVANT
Q2: Should app.{verb} take middle ware before final handler, or are these verb fns meant to be single handler end points?

Note1: I have looked at the types that are throwing in types/express-serve-static-core, they seem to have no changes since v4. This was a quick look.

Will get to more work over the weekend

[brettearle]

It seems that types for 5 are working as intended because next is the intention of middleware instead of returning directly out of them.
This is pending answers from library authors as I don't know the intentions for 5

[brettearle]

Related issue #5987

[DylasX]

Hey @tanmayvaij hope you find well, so basically something that you can do with that version of @types/[email protected] is changing a little bit your approach instead of using return res.json you can use the next approach

export const tokenVerifier =   (
  req: Request,
  res: Response,
  next: NextFunction
): void => {
  try {
    const authHeader = req.headers.authorization;

    if (!authHeader) 
      return next(JSON.stringify({err: "authorization token was not provided",isSucess: false}));

    const token = authHeader!.split(" ")[1];

    req.user = verify(
      token,
      process.env.FLEXIBASE_AUTH_SECRET_KEY!
    ) as JwtPayload;

    next();
  } catch (err) {
    return next(JSON.stringify({ isSucess: false, err }));
  }
};

[DylasX]

This issue is related to this interface in express-serve-static-core

export interface RequestHandler<
    P = ParamsDictionary,
    ResBody = any,
    ReqBody = any,
    ReqQuery = ParsedQs,
    LocalsObj extends Record<string, any> = Record<string, any>,
> {
    // tslint:disable-next-line callable-types (This is extended from and can't extend from a type alias in ts<2.2)
    (
        req: Request<P, ResBody, ReqBody, ReqQuery, LocalsObj>,
        res: Response<ResBody, LocalsObj>,
        next: NextFunction,
    ): void | Promise<void>;    
}

adding the Promise<void> in the types/[email protected] is causing this type issue so that's why it's working in previous versions because the interface returned is only void