Export a named export for each HTTP method instead.(Next.js 15)

// src/app/api/product/route.ts
import prisma from '@/prisma/prisma'
import type { NextApiRequest, NextApiResponse } from 'next'

// GET /api/product
export default async function handle(req: NextApiRequest, res: NextApiResponse) {
  if (req.method === 'GET') {
    try {
      const result = await prisma.products.findMany()
      res.status(200).json(result)
    } catch (error) {
      res.status(500).json({ error: 'Failed to fetch products' })
    }
  } else {
    res.setHeader('Allow', ['GET'])
    res.status(405).end(`Method ${req.method} Not Allowed`)
  }
}

import prisma from '@/prisma/prisma'
import type { NextApiRequest, NextApiResponse } from 'next'

export const GET = async (req: NextApiRequest, res: NextApiResponse) => {
  try {
    const result = await prisma.product.findMany();
    res.status(200).json(result);
  } catch (error) {
    res.status(500).json({ error: 'Failed to fetch products' });
  }
};