Property 'authorization' does not exist on type 'Request'

Question

Consider this code:

  setContext(async (req, { headers }) => {
    const token = await getToken(config.resources.gatewayApi.scopes)

    const completeHeader = {
      headers: {
        ...headers,
        authorization:
          token && token.accessToken ? `Bearer ${token.accessToken}` : '',
      } as Express.Request,
    }

    console.log('accessToken: ', completeHeader.headers.authorization)
    return completeHeader
  })

Which generates the following TS error:

Property 'authorization' does not exist on type 'Request'.

This comes from trying to access completeHeader.headers.authorization. The property authorization is indeed not available on the Express.request interface. It's strange that TypeScript can't infere the type from the literal object, which clearly is of type string. When not defining the type as Express.Request an error is thrown about an unsafe any assignment.

Is it required to create a new TS interface just for this one field? Or are we using an incorrect type? The field authorization looks to be like a commonly used field for sending tokens.

Answer 1

The reason is because you're coercing completeHeader.headers into the Express.Request type. The coerced type overrides the inferred type.

What you can do, is expand that coerced type by doing the following:

as Express.Request & { authorization: string }

or you could create an entirely new type:

type AuthorizedRequest = Express.Request & { authorization: string };
...
as AuthorizedRequest 

Answer 2

in my case, I needed to add user & I got error in headers with authorization(req.headers.authorization), me resolve was:

Case 1: 1.1. Where was error(req.headers.authorization), but before i had got similar error but with user:

import { IAuthRequest } from "./../types/user.type";

const checkAuth =
    () => async (req: IAuthRequest, res: Response, next: NextFunction) => {
        try {
            //2. Second i got error here(main problem)
            //i got if, i set <req:IRequestUser> for resolve 
            //problem with <req.user>: Property 'authorization' 
            //does not exist on type 'Headers'.
            //And you need to change <req: IAuthRequest>, and 
            //resolve problems
            if (!req.headers.authorization) throw new Error("Please log in");

            const token = req.headers.authorization.split(" ")[1];

            if (!process.env.SECRET_ACCESS_TOKEN)
                throw new Error("Please create <SECRET_ACCESS_TOKEN> in .env file");

            const { decoded, expired } = Jwt.verifyJwtToken(
                token,
                process.env.SECRET_ACCESS_TOKEN
            );

            if (expired) return res.status(401).send("Token has been expired");

            //1. first error here
            //before(Property 'authorization' does not exist on 
            //type 'Headers'.) i have got error here(Property 
            //'user' does not exist on type 'Request'.), if 
            //<req: Request>, you can try resolve this problem
            //<req: IRequestUser> and after this, i got error
            //with req.headers.authorization (see <2. Second i 
            //got error ...>, code above)
            req.user = decoded; 

            next();
        } catch (err) {
            return res.status(400).send(err);
        }
    };

1.2. In folder named like "types", i have created file <user.type.ts> and added:

export interface IUserData {
    _id: string;
    email: string;
    username: string;
}

export interface IRequestUser extends Request {
    user: IUserData;
}

export type IAuthRequest = IRequestUser & {
    headers: { authorization: string };
};

You need just delete comments and code above will work correctly, comment only for understanding what was in code before error, and how i resolve this problems

Case 2: after a while I found an even easier way:

import { IAuthRequest } from "./../types/user.type";

const checkAuth =
    () => async (req: Request, res: Response, next: NextFunction) => {
        try {
            req as IAuthRequest;

            //your code...

            next();
        } catch (err) {
            return res.status(400).send(err);
        }
    };

i hope that maybe it will help to someone