Use Mongo in Next.JS API routes

1. Install mongoose
2. Create a mongodb.js file inside the /api/ folder and write the mongoose configuration here.

import mongoose from "mongoose";

const connectDB = (handler) => async (req, res) => {
  if (mongoose.connections[0].readyState) {
    return handler(req, res);
  }

  await mongoose.connect(mongo_uri,
  {
    useUnifiedTopology: true,
    useNewUrlParser: true,
  });

  return handler(req, res);
};

export default connectDB

3. Now, inside the index.js file inside the /api folder, add the following.

import User from "./model/user"; // Your mongoose model
import connectDB from "./mongodb";

async function handler(req, res) {
  // Your handler code here...
}
export default connectDB(handler);

connectDB function will take the handler function and return an async function which will check if we already have a mongo connection. If we already have the connection, then we will return the handler function along with the req and res object, otherwise, we will first establish a mongo connection with mongoDB URI and then return the handler function with req and res object.