Environment

System:
OS: Linux 5.15 Ubuntu 20.04.6 LTS (Focal Fossa)
CPU: (2) x64 Intel(R) Xeon(R) Platinum 8272CL CPU @ 2.60GHz
Memory: 1.94 GB / 3.82 GB
Container: Yes
Shell: 5.0.17 - /bin/bash
Binaries:
Node: 20.3.0 - ~/nvm/current/bin/node
Yarn: 1.22.19 - /usr/bin/yarn
npm: 9.6.7 - ~/nvm/current/bin/npm
pnpm: 8.6.2 - ~/nvm/current/bin/pnpm

Reproduction URL

https://github.com/muckee/NextAuth-cannot-access-query-prop-of-res-object

Describe the issue

When attempting to follow the NextAuth documentation to implement advanced initalisation using the Next.js AppRouter, it is not possible to implement conditions within the auth route, because res.query does not exist.

My implementation is as follows:

const auth = async (
  req,
  res,
) => {

  const authOptions = {
    providers: [
      discordProvider,
    ],
    session: {
      strategy: "jwt",
    },
    secret: process.env.NEXTAUTH_SECRET,
    callbacks: {
      async session({ session, token }) {
        // @ts-ignore
        session.publicKey = token.sub;

        if (session.user) {
          session.user.name = token.sub;
          session.user.image = `https://ui-avatars.com/api/?name=${token.sub}&background=random`;
        }

        return session;
      },
    }
  };

  // ERROR: `req does not have a property named 'query'`
  // Comment out lines 39 - 43 and there will not be an error
  const isDefaultSigninPage =
    req.method === "GET" && req.query.nextauth.includes("signin");
  if (isDefaultSigninPage) {
    providers.pop();
  }

  return await NextAuth(req, res, authOptions);
}

export {
  auth as GET,
  auth as POST,
};

I've tried looking through the res object to see if the properties have been renamed, but couldn't see anything.

Other people with the issue have reverted to using the pages/ folder, but I want to find a solution which uses AppRouter.

I've also seen some people mention the issue occurring when they use getServerSideProps(), but of course that isn't relevant here.

I've reproduced the issue in a GitHub codespace based on the next-auth-example template and attached a link to the result

How to reproduce

• Create a new Next.js application with npx create-next-app ... or yarn dlx create-next-app.
• Ensure that env vars are set properly.
• Follow the NextAuth documentation to implement the NextAuth route at src/app/api/auth/[...nextauth]/route.js.
• Attempt to add a condition which checks whether req.query.nextauth includes 'signin', following the pattern described in the official documentation.

Provided that the application is properly configured and the file structure adheres to the AppRouter pattern (does not use the pages/ folder), this minimal setup should throw an error whenever the user attempts to visit any page which attempts to load an existing session, or click on a button which implements the 'signIn' function.

Expected behavior

The app should function properly and the req object should contain a query prop, or the NextAuth documentation should be updated to include whatever migration steps must be made.