It is a simple conditional process, but the session is always null.

[kkh975]

This is a typical flow of web services.
"/join page", I would like to deliver the nickname, agreement on terms and conditions, and Google Profile to the server together.
But, I can't read Google Profile.

api/auth/[...nextauth]/route.ts

export const authOptions = {
  secret: process.env.NEXTAUTH_SECRET,
  session: {
    strategy: "jwt",
  },
  providers: [
    GoogleProvider({
      clientId: process.env.NEXT_PUBLIC_GOOGLE_CLIENT_ID,
      clientSecret: process.env.NEXT_PUBLIC_GOOGLE_CLIENT_SECRET,
    }),
  ],
  callbacks: {
    async signIn({ user, account, profile }) {
      if (account?.provider === "google") {
        if (!profile) {
          throw new ReferenceError();
        }
        const existingUser = await userService.findUser({
          email: profile.email,
        });
        user.isNewUser = existingUser === null;

        if (existingUser) {
          user.id = existingUser.id;
          user.name = existingUser.name;
          user.email = existingUser.email;
          user.picture = existingUser.picture;
          return "/main";
        } else {
          user.name = profile.name;
          user.email = profile.email;
          user.email_verified = profile.email_verified;
          user.picture = profile.picture;
          return "/join";
        }
      }
      return false;
    },
  },
} as NextAuthOptions;

const handler = NextAuth(authOptions);

export { handler as GET, handler as POST };

join/page.tsx

"use client";

import { useSession } from "next-auth/react";

function JoinPage() {
  const { data: session, status } = useSession();

  console.log("JoinPage > session: ", session, status); // always is null

  return <div>join do...</div>;
}

export default JoinPage;

[davidpc-pg]

It looks like you're redirecting from the signIn callback which cancels the authentication flow. If you want to add information to the session use the jwt and session callbacks. See the examples here: https://next-auth.js.org/configuration/callbacks

[kkh975]

@davidpc-pg, thanks for reply.
But, It doesn't work.
I wrote down on below.

const authOptions = {
  secret: process.env.NEXTAUTH_SECRET,
  session: {
    strategy: "jwt",
  },
  providers: [
    GoogleProvider({
      clientId: process.env.NEXT_PUBLIC_GOOGLE_CLIENT_ID,
      clientSecret: process.env.NEXT_PUBLIC_GOOGLE_CLIENT_SECRET,
    }),
  ],
  callbacks: {
    async signIn({ user, account, profile }) {
      if (account?.provider === "google") {
        if (!profile) {
          throw new ReferenceError();
        }
        const existingUser = await userService.findUser({
          email: profile.email,
        });
        user.isNewUser = existingUser === null;

        if (existingUser) {
          user.id = existingUser.id;
          user.name = existingUser.name;
          user.email = existingUser.email;
          user.picture = existingUser.picture;
          return "/main";
        } else {
          user.name = profile.name;
          user.email = profile.email;
          user.email_verified = profile.email_verified;
          user.picture = profile.picture;
          return "/join";
        }
      }
      return false;
    },
    async jwt({ token, account, user }) {
      if (account) {
        token.isNewUser = user.isNewUser;
        token.id = user.id;
        token.name = user.name;
        token.email = user.email;
        token.email_verified = user.email_verified;
        token.picture = user.picture;
      }
      return token;
    },
    async session({ session, token, user }) {
      if (token) {
        session.user.isNewUser = token.isNewUser;
        session.user.id = token.id;
        session.user.name = token.name as string | undefined;
        session.user.email = token.email as string | undefined;
        session.user.picture = token.picture as string | undefined;
        session.user.email_verified = token.email_verified;
      }
      return session;
    },
  },
}

[davidpc-pg]

It appears you're still redirecting from signIn which cancels the authentication flow. You should only return true or false from signIn.

[kkh975]

@davidpc-pg, thank for reply.
When I look at the official document here, it seems that it can also be returned as a string. Is it possible only if it is false when it is returned as a string?

[davidpc-pg]

Right. The second note in the section you linked to explains that redirecting (which is what you're doing if you return a string) cancels the authentication flow.