express-jwt - Show permission for debug

Question

It's possible show in error middleware what permissions are needed?

//User don't have this permission
app.post("/", guard.check(permissions.$("admin")), (req, res) => {
  return new Area(req.body)
    .save()
    .then(area => {
     ///....
    })
    .catch(err => next(err))
})

Error middleware

I would like to show permission here in a console.log()

app.use(function (err, req, res, next) {
   
  
  if (err.code === "invalid_token") {
    return res.status(401).send("...")
  }

  if (err.code === "credentials_required") {
    return res.status(401).send("...")
  }

  //...
})

Answer 1

You can wrap guard.check middleware into another middleware, and you can put the required permissions to req object, and then you can get it in the error handler middleware.

const customGuard = (permissions) => { // middleware factory
  return (req, res, next) => { // return a middleware function
    req.requiredPermissions = permissions; // store `permissions` in `req.requiredPermissions`
    guard.check(permissions)(req, res, next); // check your permissions with express-jwt-permissions's guard
  }
}

Usage, replace

app.post("/", guard.check(permissions.$("admin"))
...

by

app.post("/", customGuard(permissions.$("admin"))
...

Then, in your Error middleware

app.use(function (err, req, res, next) {

  console.log("Required permissions: ", req.requiredPermissions); // here

  if (err.code === "invalid_token") {
    return res.status(401).send("...")
  }

  if (err.code === "credentials_required") {
    return res.status(401).send("...")
  }

  //...
})