thundra-mongo-driver-working-example.js

"use strict";
const thundra = require("@thundra/core")();
const MongoClient = require('mongodb').MongoClient;
const MONGODB_URI = process.env.MONGODB_URI; 

let cachedDb = null;

function connectToDatabase (uri) {
  console.log('=> connect to database');

  if (cachedDb) {
    console.log('=> using cached database instance');
    return Promise.resolve(cachedDb);
  }

  return MongoClient.connect(uri)
    .then(db => {
      cachedDb = db;
      return cachedDb;
    });
}

function queryDatabase (db) {
  console.log('=> query database');

  return db.db("test").collection('items').find({}).toArray()
    .then(() => { return { statusCode: 200, body: 'success' }; })
    .catch(err => {
      console.log('=> an error occurred: ', err);
      return { statusCode: 500, body: 'error' };
    });
}

module.exports.handler = thundra((event, context, callback) => {
  context.callbackWaitsForEmptyEventLoop = false;

  console.log('event: ', event);

  connectToDatabase(MONGODB_URI)
    .then(db => queryDatabase(db))
    .then(result => {
      console.log('=> returning result: ', result);
      context.done(null, result);
    })
    .catch(err => {
      console.log('=> an error occurred: ', err);
      context.fail(error);
    });
});