node.js mongo db write concern - node.js

Question

I am running node.js 10.22, windows 8 and mongodb not sure what version, but I just downloaded it today, when I run my code I am getting a message, please ensure you set the default write concern, I am trying to follow a YouTube video, and there is mention of this, and I am finding little about it on the internet, from what i found, when I set the db i should set j:true, or safe : true/false, but neither not working for me. I do get the console log that I'm connected and the host and port, but then I get the write concern message and can't type or do anything.
var mongo = require('mongodb');
var host = "127.0.0.1";
var port = mongo.Connection.DEFAULT_PORT;
var db = new mongo.Db("nodeintro", new mongo.Server(host,port,{Fsync: true}));
db.open(function(error){
console.log("we are connected"+host + port);
})
Tried this all type of ways as well, still no luck, best i did was get back to the db write concern message, but was not able to even connect this time. What I'm really looking for is to be able to insert anything in mongo db, and i can figure out the rest.
var Db = require('mongodb').Db;
var Connection = require('mongodb').Connection;
var Server = require('mongodb').Server;
var BSON = require('mongodb').BSON;
var ObjectID = require('mongodb').ObjectID;
var host = "127.0.0.1";
var port = mongo.DEFAULT_PORT;
ArticleProvider = function(host, port) {
this.db= new Db('node-mongo-blog', new Server(host, port, {auto_reconnect: true}, {}));
this.db.open(function(error){
if(error){
console.log(error)
}
else{
console.log(port,host)
}
});
};
ArticleProvider(host,port)

Answer 1

When using mongodb-native directly, you should now use MongoClient.connect to open a database connection pool. It will set a default write concern for you.
var mongodb = require('mongodb');
mongodb.MongoClient.connect('mongodb://localhost/nodeintro', function(err, db) {
// db is your open nodeintro database connection pool here
});
MongoClient was a somewhat recent addition so the tutorial you're working from likely pre-dates it.

Answer 2

If you use {w:1} parameter in your insert or update operation, you might give this error. To overcome you can use {journal:true} parameter in your db settings.
For instance;
var Db = require('mongodb').Db,
MongoClient = require('mongodb').MongoClient,
Server = require('mongodb').Server,
ReplSetServers = require('mongodb').ReplSetServers,
ObjectID = require('mongodb').ObjectID,
Binary = require('mongodb').Binary,
GridStore = require('mongodb').GridStore,
Grid = require('mongodb').Grid,
Code = require('mongodb').Code,
BSON = require('mongodb').pure().BSON;
var db = new Db('Your DB Name', new Server('192.168.170.128', 27017), { journal : true });
db.open(function(err, db) {
var collection = db.collection('user');
collection.findOne({'_id':req.session.User._id}, function(err, user){
// some codes what do you want
collection.save( user, {w: 1}, function(err, user_id) {
// just close the db connection
db.close();
});
});
});