用 Typescript 解构 object

Question

I have the following code however it gives me error. I'm not sure what's the correct way to do this. The error says

Type 'CookieSessionObject | null | undefined' is not assignable to type '{ token: string; refreshToken: string; }'.
  Type 'undefined' is not assignable to type '{ token: string; refreshToken: string; }'

...
  namespace CookieSessionInterfaces {
    interface CookieSessionObject {
      token?: string;
      refreshToken?: string;
    }
  }
}

const currentUser = async (req: Request, res: Response, next: NextFunction) => {
  const { token, refreshToken }: { token: string, refreshToken: string } = req.session;
...

Also req.session?.token and req.session?.refreshToken work.

Answer 1

req.session can be null or undefined . Hence in your case, you can handle it as:

type Tokens  = {
    token?: string, 
    refreshToken?: string
}

const { token, refreshToken }: Tokens = req.session || {token: null, refreshToken: null}

else, if session is undefined or null , you can throw an exception which you can catch later and handle accordingly.

if (!req.session) {
    throw new UnauthorizeException()
}

const { token, refreshToken }: Tokens = req.session

UnauthorizeException could be your custom exception or you can use some generic exception as well.

If you are implementing callback, you have to call callback instead of throwing exception.