NodeJS 'mongodb' client update function not working sometimes - node.js

Question

mongodb client version: 3.1.10
I am using hosted mongo db server on Mlab.com: Shared Production-Ready cluster.
var dbo = db.db(DB);
var collection = dbo.collection('schedule');
var query = {email:userEmail};
let availability = (availabilityArg==="offQ")?"no":"yes";
let note = (availabilityArg==="offQ")?"Off Queue":"";
var data = {available:availability,notes:note};
collection.update(query,{$set:data},function(err,data){
if(err)
console.log("DB find error.");
else{
console.log(userEmail+((availabilityArg==="offQ")?" off the queue":" back in queue"));
}
});
The above works 95% of the time. 5% of the time, the DB does not get updated at all.
95%: The DB get's updated based on the availabilityArg. If it is offQ, the available attribute will be set to no. If it is onQ, the available attribute will be set to yes. The notes attribute also gets updated accordingly.
5%: The DB does not get updated at all. There's no change to the available attribute and the notes attribute. Though I see the console.log statement with the email ID and the off the queue/back in queue message.
It just doesn't make sense.
PS:
function(db,userEmail, availabilityArg)

Answer 1

I took your code and re-imagined it as follows, I hope it helps.
/*
I am not sure what is going on behind here
so I'll just comment it out, and show you
an implementation that works, which you can
repurpose.
*/
// var dbo = db.db(DB);
// var collection = dbo.collection('schedule');
/*
NOTE: Below is the an example model for handling data using mongoose,
This should be in a separate file which you would import
*/
const mongoose = require('mongoose');
const schema = new mongoose.Schema({
email: {
required: true,
type: String,
require: true
},
availability: {
required: true,
type: String,
default: ''
},
notes: {
required: true,
type: String,
default: ''
}
});
// If in the same file (not advisable)
const Schedule = mongoose.model('Schedule', schema, 'schedule_collection');
// Or export (advisable)
module.exports = mongoose.model('Schedule', schema, 'schedule_collection');
// NOTE: Below is a re-imagined version of your code
const findQuery = { email: userEmail };
const availability = availabilityArg === 'offQ' ? 'no' : 'yes';
const notes = availabilityArg === 'offQ' ? 'Off Queue' : '';
// NOTE: For updating the document
const updateQuery = {
availability: availability,
notes: notes
};
// NOTE: Using findOneAndUpdate of the Model
Schedule.findOneAndUpdate(findQuery, updateQuery, (err, _) => {
if (err)
console.log("DB error.");
else {
console.log(userEmail + ((availabilityArg === "offQ") ? " off the queue" : " back in queue"));
}
});