MongoDB update if user not exists - node.js

Question

I have a problem to update user if his/her name is not available in my database
I thought if my function "User.findOne" doesn't find a user in my mongodb it can update database. Unfortunately nothing happens. I get only output "Hello Anna you are new here!" My name is not saved into my mongodb
Could somebody smart give me please a tip how can I save username if it is not in my database
var User = require('./user');
var myName = this.event.request.intent.slots.first_name.value;
self = this;
User.findOne({ name: myName }, function(err, user) {
if (err ||!user){
var userSave = new User({
name: myName
});
userSave.save(function (err, results) {
console.log(results);
self.emit(':ask',
"Hello "+ myName +"you are new here!")
});
}
else {
self.emit(':ask',
"Hello "+ myName +" you are not new!")
}
});
My mongoose model code:
//user.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
mongoose.connect("mongodb://c******mlab.com:***/users");
var userSchema = new Schema({
name: String,
userId: { type: String, required: false, unique: true }
});
var User = mongoose.model('User', userSchema);
module.exports = User;

Answer 1

var User = require('./user');
var myName = this.event.request.intent.slots.first_name.value;
self = this;
User.findOne({
name: myName
}, (err, user) => {
if(err) throw err;
if(user) {
self.emit(':ask', `Hello ${myName} you are not new`);
} else {
User.create({
name: myName
}, (err, result) => {
if(err) throw err;
console.log(result);
self.emit(':ask', `Hello ${myName} you are new here!`);
})
}
});
this should work.

Answer 2

The line if (err || !user) is confusing to read, and in this style you're mixing error handling (if (err)) and a condition in your code that you expect to hit (if (!user)). I suggest you separate them so the code is easier to read and debug.
For example, using plain Javascript and the MongoDB node driver:
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect('mongodb://localhost/test', function(err, conn) {
// connection error handling
if (err) {
console.log('Connection error: ' + err);
}
conn.db('test').collection('test').findOne({name:'abc'}, function(err, doc) {
// findOne error handling
if (err) {
console.log('Error: ' + err);
}
// if document exists
if (doc) {
console.log('Document found: ' + JSON.stringify(doc));
}
// if document doesn't exist
else {
console.log('Document not found');
}
conn.close();
});
});
If the database contains the user abc, the output would be:
$ node script.js
Document not found
If the user abc exists:
$ node script.js
Document found: {"_id":0,"name":"abc"}
I believe using a similar pattern you can modify your code to do what you need.