Add more details other than name, image, and id to NextAuth session

Question

I have implemented next-auth in Next.js project and I have this JWT and session:

export const { signIn, signOut, auth } = NextAuth({
  ...authConfig,
  providers: [
    CredentialsProvider({
      async authorize(credentials) {
        try {
          const user = await login(credentials);
          return user;
        } catch (error) {
          return null;
        }
      },
    }),
  ],
  callbacks: {
    async jwt({ token, user }: { token: any; user: any }) {
      if (user) {
        token.id = (user as CustomUser).id;
        token.username = (user as CustomUser).username;
        token.img = (user as CustomUser).img;
        token.isAdmin = (user as CustomUser).isAdmin;
      }
      return token;
    },
    async session({ session, token }: { session: any; token: any }) {
      if (token) {
        session.user = {
          name: token.username,
          image: token.img,
          id: token.id,
          isAdmin: token.isAdmin,
        };
      }
      return session;
    },
  },
});

I am adding isAdmin also in session so that I can use it in my code.

const session = await auth();
console.log(session?.user?.isAdmin)

And I am getting this error message:

Property 'isAdmin' does not exist on type '{ name?: string | null | undefined; email?: string | null | undefined; image?: string | null | undefined; }'.ts(2339)

Can someone tell me how to add more data in session?

This is my user:

 {
  _id: new ObjectId('random'),
  username: 'admin',
  email: '[email protected]',
  password: '',
  isAdmin: true,
  isActive: true,
  phone: '',
  address: 'no ',
}

Answer 1

You need to create a types/next-auth.d.ts file, and add the additional field you want to the session, as the doc shows:

import NextAuth, { DefaultSession } from "next-auth"

declare module "next-auth" {
  interface Session {
    user: {
      isAdmine?: boolean
    } & DefaultSession["user"]
  }
}