Use Mongoose.js as Fastify plugin

fastify-mongoose-plugin.js

const dotenv = require('dotenv').config();
const mongoose = require('mongoose');
const fp = require('fastify-plugin');

async function mongooseConnect(fastify, options, done) {
  try {
    await mongoose.connect(process.env.DB_URI);
    console.log('DB connected!');
  } catch (err) {
    console.log(err);
  }

  fastify.decorate('db', mongoose.connection); // usage example: `fastify.db.users.find({})`

  done();
}

module.exports = fp(mongooseConnect);