How to decode Auth0 custom claim?

[vnugent]

Hi,
I have an Auth0 action that initializes some user metadata before each login. For the sake of this question, let's say I'm setting a custom claim, https://example.com/foo = bar.

How do I retrieve this value in next-auth? The token contains the standard, name, email, picture, sub, accessToken, but not the namespaced custom claim. Thank you for your help.

PS: I can use Auth0 management API to get the info. It's the extra call that I'm trying to avoid.

PPS: It's working for me now. Make sure you clean up nextjs cache (rf -rf .next). To make Typescript happy with new field(s) you're adding to token and session , see https://next-auth.js.org/getting-started/typescript#module-augmentation

Auth0 Post login action

exports.onExecutePostLogin = async ({ user }, api) => {
   const ns ='https://example.com/'
   api.idToken.setCustomClaim(ns + "foo",  'bar')
}

[...nextauth].ts

...
  callbacks: {
    async jwt ({ token, account, profile, user }) {
      console.log('#jwt', token, account, profile, user)
      if (account?.access_token != null) {
        token.accessToken = account.access_token
      }
      if (profile?.sub != null) {
        token.id = profile.sub
      }
 
      // profile is populated when the user first signs in
      if (profile?.foo != null) {
        token.foo = profile.foo as string
      }

      return token
    },
...

[vnugent]

See updated post