Cron job that checks for date expiration - node.js

Question

Let's take the following example:
I have two mongoDb collections named user and products. A user can add unlimited products, but each product expires in 5 days and it has to be dynamically removed from the db when it expires.
user.js
const UserSchema = mongoose.Schema(
{
username: { type: String },
email: { type: String },
timezone: { type: String },
products: [{ type: Schema.Types.ObjectId, ref: 'Products' }]
}
)
export default mongoose.model('User', UserSchema);
products.js
var RunSchema = mongoose.Schema(
{
name: { type: String },
completedAt: { type: Date }
}
)
export default mongoose.model('Run', RunSchema);
Is there another way of doing this in nodejs rather than having one cron job which runs every day and checks all documents from the products collection?
I'm thinking about a solution where a each user can have a cron job that starts once they add a product...

Answer 1

It is too late answer the question even though , I would like to give alternative operation with minimal operation and without Cron Job
If you want remove product document after creation of 5 day's interval then you can achieve with 2 line of code in model itself.
You have add one property i.e(expireAt) in model and pass the interval to that property with help of moment npm library
var RunSchema = mongoose.Schema(
{
name: { type: String },
completedAt: { type: Date },
expireAt: {
type: Date,
default: moment(new Date()).add("5", "days"),
expires: 432000000
}
}
)
export default mongoose.model('Run', RunSchema);
after creation of product document date and time . it will automatically remove document from collection of every 5 days of interval.

Answer 2

First method:
You can add a cron in NodeJs and it will execute your task every x
Example:
Add the package cron in your project.
npm i cron -S
Create a file cron.js
'use strict';
let express = require('express'),
CronJob = require('cron').CronJob,
moment = require('moment'),
mongoose = require('mongoose');
Collection = mongoose.model('Collection');
var collection = {
clean : function() {
// Each hour
new CronJob('0 * * * *', function() {
console.log("Hello I'm Cron!");
// Delete all the product expired of your db
// Your code ...
}, null, true, 'Europe/Paris');
}
}
module.exports = {
init : function() {
return (
collection.clean()
)
}
}
In your server.js, add the following code to initialize the cron
/**
* Init cron tasks
*/
var cron = require('./cron');
cron.init()
Second method:
Setting expiry time in your model, check that answer for more informations.