MongoDb 和 Node.js

Question

so I am working with node.js and mongodb and I am a rookie The below us my code:

const MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://localhost:27017/myproject';
MongoClient.connect(url,function(err,db){
 if (err){
     return console.dir(err);
 }
 console.log('connected to mdb');
 InsertDoc(db,function(){
  db.close(); 
 })
 });

 const InsertDoc= function(db, callback){

 const collection = db.collection('users');
 collection.insert({
     name : 'vishnu',
     email:'vishnu@123'
 },
 function(err,result){
     if(err){
         return console.dir(err);
     }
     console.log('inserted doc');
     console.log(result);
     callback(result);
 });
 }

 ERROR: TypeError: db.collection is not a function

I am not sure where I have gone wrong kindly let me know the mistake

Answer 1

The callback from connect will return you an instance of MongoClient and an instance of Db , as mentioned in official Mongodb Node driver documentation, look at the second example

https://mongodb.github.io/node-mongodb-native/4.1/classes/MongoClient.html

Once you obtain the collection you will have to get the db by using client.db(dbName) which will give you the db object for creating a collection .

// Connect using the MongoClient.connect static method
const MongoClient = require('mongodb').MongoClient;

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

// Connect using MongoClient
MongoClient.connect(url, function(err, client) {
  const db = client.db("myproject");

  const collection = db.collection("users");
  // do your thing

  client.close();
});
`