TypeError: db.collection is not a function

Question

I am trying to post data to database that I have created on mLab and I am getting this error but I don\'t know whats going wrong.I also have read previously asked question o

Answer 1

Had this issue as well, I was following a tutorial in which the presenter was using the collection as a function. It never worked for me. What I discovered was that the presenter was using version 2.3.4 of the mongodb npm module. the module is well into version 3.x.x now. When I changed the package.json file to request the 2.x.x version of the mogodb npm module, suddenly everything worked.

What I believed happened was that the module was altered to change the collection into a different object. Don't know how to use the new version but if you specify that you want the 2.x.x version, the old way should work. Specifically I can confirm that (coming from my package.json file, "dependencies" section) "mongodb": "^2.2.31" works.

Best way:

$> npm install mongodb@2.2.31 --save

Answer 2

const MongoClient = require('mongodb').MongoClient;

//connection url

 const url = 'mongodb://localhost:27017/myproject';

 MongoClient.connect(url,{useNewUrlParser: true},(err,client)=> {
  if(err) {
    return console.dir(err)
  }

   console.log('Connected to MongoDB')

  //get the collection
  let db = client.db('myproject');
  db.collection('users').insertOne({
  name: 'Hello World',
  email: 'helloworld@test.com'

  },(err,result)=> {
  if(err) {
      return console.dir(err)
  }
  console.log("Inserted Document");
  console.log(result);

     });
   });

Answer 3

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) => {
...

db -> client

module.exports = function(app, client) {
  var db = client.db("name");
  app.post('/notes', (req, res) => {
  const note = { text: req.body.body, title: req.body.title };
  db.collection('notes').insert(note, (err, result) => {
...

Answer 4

In your package.json.

make sure the following versions look like this:

"nodemon": "^1.12.1"
"mongodb": "^2.2.33"

the above nodemon and mongodb versions work together without any errors. so your package.json should look something like this:

    {
  "name": "myapi",
  "version": "1.0.0",
  "description": "Json Api",
  "main": "server.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "dev": "nodemon server.js"
  },
  "author": "Riley Manda",
  "license": "ISC",
  "dependencies": {
    "body-parser": "^1.18.2",
    "express": "^4.16.2",
    "mongodb": "^2.2.33"
  },
  "devDependencies": {
    "nodemon": "^1.12.1"
  }
}

dont forget to run npm install after downgrading

Answer 5

Uninstalling existing mongodb package and reinstalling using the following commands resolved the issues for me. :)

npm uninstall mongodb --save

npm install mongodb@2.2.33 --save

PS: Thanks to @MihirBhende and @yaxartes

FYI,

Prefer non-rc releases from https://github.com/mongodb/node-mongodb-native/releases, if you are new to the field.

Answer 6

In your server.js, you are passing empty object where you need to pass database as second argument as its what your routes/index.js export function expects.

PFB updated server.js :

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({extended: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); 
    });

});