Can I override any type property in Typescript?-CodePudding

I'm trying to attach my custom types into Express's Request/Response interface.

But some properties are of type any, so I'm having really hard to override it.

ex:

// @types/expres-server-static-core
interface Request {
  cookies: any;
}

// my.ts
import type {Request} from 'express';

type MyCookies = {
  'apple'?: string;
  'banana'?: string;
}

interface MyRequest extends Request {
  cookies: MyCookies
}

// my-usecase.ts
const request: MyRequest = /* */; // MyRequest | Request
request.cookies; // still has any type because MyCookies | any will be any type

I know anytype is the top type of typescript so customized cookiesproperty will be ignored.
So I'm using like:

const myRequest: MyCookies = req.cookies;

It can solve this problem but I don't want to declare MyCookies constants; req.cookies = MyCookies is easier to use.

Is there any good way to override any type property?

CodePudding user response：

Do not override default properties like that, because at "runtime" there is no guarantee req.cookies will exist. So to get correct type, do type narrowing.

const handler = (req: Request, res: Response) => {
  if (!req.cookies) throw new Error('unauthorised')
  if (!req.cookies['cookie_name_1'] || typeof req.cookies['cookie_name_1'] !== 'string') throw new Error('unauthorised')
  const cookie_name_1 = req.cookies['cookie_name_1'] // cookie_name_1 is string
}

Above one ensures existence of req.cookies at both runtime & compilation.

CodePudding user response：

How about extending module?

declare global {
  namespace Express {
    export interface Request {
      cookies: {
       'apple': string;
       'banana': string;
      }
    }
  }
}