Missing Global Prisma Client (Crucial for Development)

[codeCraft-Ritik]

Issue Summary

In a Next.js environment, especially during local development, the application frequently undergoes "Hot Module Replacement" (HMR). Every time you save a file, Next.js reloads the module. If your Prisma Client is initialized directly in a file that gets reloaded, it creates a new instance of PrismaClient and a new connection pool to your MongoDB database with every save.

Detailed Problem

• Connection Exhaustion: MongoDB has a limit on the number of concurrent connections it can handle. Because each new PrismaClient() instance establishes its own connection pool, you will quickly reach the database's connection limit.
• Runtime Errors: Once the limit is reached, your application will throw errors such as request to http://localhost:PORT/api/... failed or Prisma-specific timeout errors, halting development until you manually restart the server.
• Performance Degradation: Repeatedly opening and closing connection pools is resource-intensive, leading to slower API response times during your development sessions.

How to Fix This You must implement a "Singleton" pattern. This ensures that even when Next.js reloads your modules, the application checks if a Prisma instance already exists in the global object before creating a new one.

Updated Code (lib/db.js):

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

// This approach prevents multiple instances of Prisma Client in development
const prismaClientSingleton = () => {
  return new PrismaClient();
};

const globalForPrisma = global;

// Use an existing global instance or create a new one
export const prisma = globalForPrisma.prisma ?? prismaClientSingleton();

// In development, save the instance to the global object to persist across reloads
if (process.env.NODE_ENV !== "production") {
  globalForPrisma.prisma = prisma;
}

export default prisma;