If you're building a web application with Next.js and using MongoDB as your database, connecting the two can seem daunting. However, with the help of Mongoose, a popular MongoDB object modeling tool, the process can be made much simpler. In this tutorial, we'll walk through the steps required to connect MongoDB with Next.js using Mongoose.
STEPS
1. download mongodb compass
2. npm install mongoose
3. Create config and models directory
4. Add MongoDb Path in next.config.js
     const nextConfig = {
       env: {
         MONGODB_URI: "mongodb",
       },
     }
5. Inside config create dbConnect.js Write following code inside dbConnect.js
                     import mongoose from 'mongoose'
                   const MONGODB_URI = process.env.MONGODB_URI
                   if (!MONGODB_URI) {
                     throw new Error(
                       'Please define the MONGODB_URI environment'
                     )
                   }
                   let cached = global.mongoose
                   if (!cached) {
                     cached = global.mongoose = { conn: null, promise: null }
                   }
                   async function dbConnect() {
                     if (cached.conn) {
                       return cached.conn
                     }
                     if (!cached.promise) {
                       const opts = {
                         bufferCommands: false,
                       }
                       cached.promise = mongoose.connect(MONGODB_URI, opts).then((mongoose) => {
                         return mongoose
                       })
                     }
                     try {
                       cached.conn = await cached.promise
                     } catch (e) {
                       cached.promise = null
                       throw e
                     }
                     return cached.conn
                   }
                   export default dbConnect
6. Inside Models create file user.js with following code
             import mongoose, { model } from "mongoose";
             const userSchema = new mongoose.Schema({
               name: String,
               email: String,
               password: String,
             });
             export default mongoose.models.User || mongoose.model("User", userSchema);
7. Inside src\pages\api create a directory user
8. Inside user directory create index.js with following code
           import User from "../../../../models/User";
           import dbConnect from "../../../../config/dbConnect";
           dbConnect();
           export default async (req, res) => {
             const { method } = req;
             switch (method) {
               case "GET":
                 try {
                   const user = await User.find({}).sort({ _id: -1 });
                   res.status(200).json({ success: true, data: user });
                 } catch (error) {
                   res.status(400).json({ success: false });
                 }
                 break;
               default:
                 res.status(400).json({ success: false });
                 break;
             }
           };
9. Insert some documents inside MongoDB
10 Visit URL http://localhost:3000/api/user to get user list as API from MongoDB