Node js＆mongoDB - TypeError：db.collection不是函數

Question

我試圖將數據從POSTMAN發布到我在mLab上創建的外部數據庫但是我收到錯誤db.collection不是函數。

有一個類似的問題線程，但答案是不完整的，並沒有保存我給郵差給mLab的任何鍵/值。 我正在嘗試使用的代碼來自本教程： https ： //medium.freecodecamp.com/building-a-simple-node-js-api-in-under-30-minutes-a07ea9e390d2

我的代碼：

Server.js

const express  = require('express'); // Load routes application
const MongoClient = require('mongodb').MongoClient; //Load database connection application
const db = require('./config/db');
const app  = express(); // Assign express app a variable
const port = 8000; //Set local port value for server
const bodyParser = require('body-parser'); // **This has to come BEFORE routes
var assert = require('assert'); // ?
var databaseURL ='mongodb://external:api@ds123312.mlab.com:23312/soundfactory';


app.listen(port, () => {
  console.log('')
  console.log('We are live on ' + port);
  console.log('')
});


MongoClient.connect(databaseURL, function(err, db) {
  assert.equal(null, err);
  console.log("API has succesfully connected to Sound Facotry mlab external database.");
  console.log('')
  db.close();
});


app.use(bodyParser.urlencoded({ extended: true }))
require('./app/routes')(app, {}); //Must come AFTER express w/ body parser

db.js

module.exports = {
  url : 'mongodb://external:api@ds123312.mlab.com:23312/soundfactory'
};

index.js

const noteroutes = require('./note_routes');
module.exports = function(app,db)
{
    noteroutes(app,db);
};

note_routes.js

module.exports = function(app, db) {
  app.post('/notes', (req, res) => {
    const note = { text: req.body.body, title: req.body.title };
    db.collection('notes').insert(note, (err, result) => {
      if (err) { 
        res.send({ 'error': 'An error has occurred' }); 
      } else {
        res.send(result.ops[0]);
      }
    });
  });
};

部分正確的代碼

server.js（部分工作的代碼，不會像我原來的server.js文件那樣拋出db.collections錯誤）

const express = require('express');
const MongoClient = require('mongodb').MongoClient;
const bodyParser = require('body-parser');
const db = require('./config/db');
const app = express();
const port = 8000;
app.use(bodyParser.urlencoded({extened:true}));
MongoClient.connect(db.url,(err,database) =>{
 if (err) return console.log(err)
//require('./app/routes')(app,{});
//check below line changed
 require('./app/routes')(app, database);
app.listen(port,() => {
    console.log("We are live on"+port); 
});
})

Answer 1

刪除node_modules文件夾並更改package.json mongodb版本

"mongodb": "^2.2.33"

並運行以下代碼：

npm install

Answer 2

更改為此require('mongodb').MongoClient;