So im completely new to NextJS and i decided to use the new app dir.
I have my loginbutton component and my api route for loggin in.
This is the api route.ts:

import { PrismaClient } from '@prisma/client';

const prisma = new PrismaClient();

export async function POST(req) {

  let {usernameValue, passwordValue} = await req.json();

  var username = usernameValue
  var password = passwordValue

  try {
    const site = await prisma.users.findFirst({
      where: {
        username: username,
        password: password,
      },
    });

    if (site) {
      return Response.json({ authenticated: true })
      
    } else {
      return Response.json({ authenticated: false})
    }
  } catch (error) {
    console.error(error);
    return Response.json({ authenticated: false, error: 'An error occured.' })
  } finally {
    await prisma.$disconnect();
  }
}

As you can see this works fine. Is there anyone who can guide me on how to set a session when authenticated is true?