Unable to get decoded payload of JWT from auth0/express-jwt library - node.js

Question

I'm trying to obtain the decoded JWT payload using the express-jwt from auth0 as a middleware in my expressjs application. For the token to be used for authentication, I have to use a custom async function to process the token first before providing it to express-jwt. I understand that I can write a custom function under the getToken parameter as documented in express-jwt as shown below, but it does not work with async function.
const jwt = require("express-jwt");
const checkJwt = jwt({
secret: 'hello world !',
algorithms: ['HS256'],
credentialsRequired: false,
getToken: function fromHeaderOrQuerystring (req) {
if (req.headers.authorization && req.headers.authorization.split(' ')[0] === 'Bearer') {
return req.headers.authorization.split(' ')[1];
} else if (req.query && req.query.token) {
return req.query.token;
}
return null;
}
});
module.exports = checkJwt;
To overcome this limitation, I included the jwt() as part of a larger middleware function that first process the token, and then providing it to jwt(). The unprocessed token is attached to my headers. My code structure is as follows:
const myMiddleware = async (req, res, next) => {
// Process Token First
const processedToken = await functionToProcessToken(req.headers.tokenLocation);
// Jwt Authentication
jwt({
secret: 'hello world !',
algorithms: ['HS256'],
credentialsRequired: false,
getToken: processedToken
});
next();
});
module.exports = myMiddleware;
While I'm able to authenticate my routes without any issue, I need to get the decoded JWT payload for further uses. By default, as written in the documentation, the decoded payload should have been attached to req.user, but when I try to console.log it, it shows undefined. I have also tried adding requestProperty but it does not work as well. The documentation for resultProperty is not very clear, so I could not get that to work too.
I very much appreciate if someone can point me towards right direction to help me achieve the expected outcome for my middleware. Thank you!