Theo's Typesafe Cult•2y ago

Typescript error when trying to access more user properties in my JWT token

Hello! I am using Next Auth and I have it built so that users will also have a username, and in my auth file, my jwt callback looks like this:

    jwt: ({ token, user }) => {
      console.log("JWT CALLBACK");
      console.log({ user });
      if (user) {
        token.id = user.id;
        token.email = user.email;
        token.name = user.name;
        token.username = user.username;
      }
      console.log({ token });
      return token;
    },

    jwt: ({ token, user }) => {
      console.log("JWT CALLBACK");
      console.log({ user });
      if (user) {
        token.id = user.id;
        token.email = user.email;
        token.name = user.name;
        token.username = user.username;
      }
      console.log({ token });
      return token;
    },

Unfortunately, I am getting this TypeScript error: Property 'username' does not exist on type 'User | AdapterUser'. After looking into it, I found that the user type is defined in the node_modules folder, and this is what both User and AdapterUser looks like:

export interface AdapterUser extends User {
  id: string
  email: string
  emailVerified: Date | null
  username: string
}
// and
export interface DefaultUser {
  id: string
  name?: string | null
  email?: string | null
  image?: string | null
  username?: string | null
}

export interface User extends DefaultUser {}

export interface AdapterUser extends User {
  id: string
  email: string
  emailVerified: Date | null
  username: string
}
// and
export interface DefaultUser {
  id: string
  name?: string | null
  email?: string | null
  image?: string | null
  username?: string | null
}

export interface User extends DefaultUser {}

As you can see I've tried adding username to either or, and both, but I'm still getting the same error (after a ts server refresh too) and my app also will not build because of it. Any help would be appreciated. Thank you!

2 Replies

delavalom•2y ago

Next-auth uses Module Augmentation to customize the types, so you don't need to change the node_modules: https://next-auth.js.org/getting-started/typescript#module-augmentation Anyways, to solve this, type the following:

import {
  type DefaultSession,
  type DefaultUser,
} from "next-auth";
import { type DefaultJWT } from "next-auth/jwt";

declare module "next-auth" {
  interface Session extends DefaultSession {
    user: {
      id: string;
      name: string;
    };
    username: string; // Here you are telling typescript that you session will have the username property, if you want your client to have access to this property
  }
  interface User extends DefaultUser {
    username: string; // the user will now have the property 
  }
}

declare module "next-auth/jwt" {
  interface JWT extends DefaultJWT {
    id: string;
    username: string; // also my jwt will have the property, I can access this property within the JWT using the getToken() helper
  }
}

export const authOptions: NextAuthOptions = {
  session: {
    strategy: "jwt",
  },
  callbacks: {
    jwt({ token, user, account }) {
      if (account && account.access_token) {
        token.id = user.id;
        token.username = user.username; // asign the value
      }
      return token;
    },
    session({ session, token }) {
      session.user.id = token.id;
      session.username = token.username; // pass the value to the client session

      return session;
    },
  },

import {
  type DefaultSession,
  type DefaultUser,
} from "next-auth";
import { type DefaultJWT } from "next-auth/jwt";

declare module "next-auth" {
  interface Session extends DefaultSession {
    user: {
      id: string;
      name: string;
    };
    username: string; // Here you are telling typescript that you session will have the username property, if you want your client to have access to this property
  }
  interface User extends DefaultUser {
    username: string; // the user will now have the property 
  }
}

declare module "next-auth/jwt" {
  interface JWT extends DefaultJWT {
    id: string;
    username: string; // also my jwt will have the property, I can access this property within the JWT using the getToken() helper
  }
}

export const authOptions: NextAuthOptions = {
  session: {
    strategy: "jwt",
  },
  callbacks: {
    jwt({ token, user, account }) {
      if (account && account.access_token) {
        token.id = user.id;
        token.username = user.username; // asign the value
      }
      return token;
    },
    session({ session, token }) {
      session.user.id = token.id;
      session.username = token.username; // pass the value to the client session

      return session;
    },
  },

Read all my comments in the code, also make sure to retrieve the username from the provider in my case using Github I get the username like this:

providers: [
    GithubProvider({
      clientId: env.NEXT_PUBLIC_CLIENT_ID,
      clientSecret: env.CLIENT_SECRET,
      profile(profile) {
        return {
          id: profile.id.toString(),
          name: profile.name,
          username: profile.login,
          email: profile.email,
          image: profile.avatar_url,
        };
      },
    }),
  ],

providers: [
    GithubProvider({
      clientId: env.NEXT_PUBLIC_CLIENT_ID,
      clientSecret: env.CLIENT_SECRET,
      profile(profile) {
        return {
          id: profile.id.toString(),
          name: profile.name,
          username: profile.login,
          email: profile.email,
          image: profile.avatar_url,
        };
      },
    }),
  ],

TypeScript | NextAuth.js

NextAuth.js has its own type definitions to use in your TypeScript projects safely. Even if you don't use TypeScript, IDEs like VSCode will pick this up to provide you with a better developer experience. While you are typing, you will get suggestions about what certain objects/functions look like, and sometimes links to documentation, examples, ...

ruhrohOP•2y ago

That is extremely helpful, thank you so much!

Gaming

Programming

Typescript error when trying to access more user properties in my JWT token