类型“字符串”上不存在属性“电子邮件”

Question

I am very new to typescrypt, and I'm currently in the process of migrating a project from JS to TS. While I was changing some things on my server endpoints, an error appeared:

Property 'email' does not exist on type 'string | JwtPayload'

This is my code so far:

try {
    const token = await TokenController.getTokenFromRequest(req);
    const decoded = jwt.decode(token);
    const user = await AuthController.getUserByMail(decoded.username); // <- Error appears here
    res.json(user);
} catch (error: any) {
    ErrorController.errorCallback(error, res);
}

I know that the error happens because I'm trying to access a property that string doesn't have. Any suggestions?

Answer 1

Create global.d.ts:

// global.d.ts
declare module "jsonwebtoken" {
    export interface JwtPayload {
        //make optional so when you try to decode stuff other than user it will show it can be undefined
        email?: string;
    }
}