Type error with express middleware generator function

Question

I have a function, that takes a middleware function, wraps it into a try catch block and then returns back a middleware function.

tryCatch.ts

import { Request, Response, NextFunction } from "express";

export default function tryCatch(controller: (req: Request, res: Response, next?: NextFunction) => Promise<any>) {
  return async function (req: Request, res: Response, next: NextFunction): Promise<void> {
    try {
      await controller(req, res, next);
    } catch (error) {
      // do some logging first, then call next
      return next(error);
    }
  }
};

Route handler

import express from 'express';
import tryCatch from './tryCatch';
import someAsyncHandler from './controller/someAsyncHandler';

const router = express.Router({ mergeParams: true });
router.post('/foo', someAsyncHandler);
//                  ^ this works
router.post('/bar', tryCatch( someAsyncHandler ));
//                  ^ this doesn't work

It gives the following error:

No overload matches this call. The last overload gave the following error.

Argument of type '(req: Request<ParamsDictionary, any, any, ParsedQs, Record<string, any>>, res: Response<any, Record<string, any>>, next: NextFunction) => Promise<...>' is not assignable to parameter of type 'Application<Record<string, any>>'.

Type '(req: Request<ParamsDictionary, any, any, ParsedQs, Record<string, any>>, res: Response<any, Record<string, any>>, next: NextFunction) => Promise<...>' is missing the following properties from type 'Application<Record<string, any>>': init, defaultConfiguration, engine, set, and 63 more. ts(2769)

Before switching to Typescript, this worked fine. What am I doing wrong or is it just Typescript?

KorbenDose · Accepted Answer · 2024-02-19 11:49:02Z

1

So I found out, what the issue was. As it often is, it was something completely different.

The actual issue was that I am using ts-node and it didn't recognize the declaration merging I did for the Response type. Funny enough, VS Code was able to recognize the correct types.

The solution was to add the --files flag to the command (see this answer). For reference, here are my settings.

package.json

{
  "scripts": {
    "dev": "nodemon"
  }
}

nodemon.json

{
  "watch": ["src"],
  "ext": "ts,json,js",
  "ignore": ["src/**/*.spec.ts"],
  "exec": "ts-node --files src/app.ts"
}

answered Feb 19, 2024 at 11:49

KorbenDose

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Type error with express middleware generator function

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