How to create a document with the data from another collection? - node.js

Question

const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const CompanySchema = new Schema(
{
companyName: {
type: String,
required: true,
unique: true
},
taxOffice: {
type: String
},
taxNumber: {
type: String
},
},
{
timestamps: true
}
);
const Company = mongoose.model('Company', CompanySchema);
module.exports = Company;
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const DateSchema = new Schema({
name: {
type: String,
unique: true,
required: true
},
companies: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Company' }]
});
const Date = mongoose.model('Date', DateSchema, 'dates');
module.exports = Date;
const router = require('express').Router();
const Date = require('../models/date');
router.route('/').get((req, res) => {
Date.find()
.then(dates => res.json(dates))
.catch(err => res.status(400).json('Error: ' + err));
});
router.route('/add').post((req, res) => {
const name = req.body.name;
const newDate = new Date({ name });
newDate
.save()
.then(() => res.json('Date added!'))
.catch(err => res.status(400).json('Error: ' + err));
});
module.exports = router;
I have 2 collections called Company and Date.
I inserted many data to Company Collection.
But I want that Company data(companies) to copied into Date Collection whenever I create a Date document.
I want to store company data as an array for each Date.
By the way don't know that my schema design is correct for the purpose. What should I do?
I want to have a Date document like:
{
name: "DECEMBER-2019",
companies: ['5e2076236664640d22515f7b', '5e2076236664640d22515f7a']
}

Answer 1

It sounds like you want to take an action whenever you create a new document in the Date collection. If you are using Atlas (MongoDB's fully managed database as a service), you can configure a Trigger to fire whenever a new document is inserted into the Date collection. Another option (regardless of whether you are using Atlas or not) is to use Change Streams to monitor changes in the Date collection. For more on how to configure these, see https://www.mongodb.com/blog/post/node-js-change-streams-and-triggers.

Answer 2

Assuming that only companies present at the time of Date Object creation should be added in Date's companies field, Then you can maintain a cache of companies ObjectIds at any point of time which will be updated for every delete/insert in Company Collection.
You can write your own function of creating a date object which will have parameter name which add the current companies ObjectIds.
Date.statics.getNewDateObject = function(name) {
let companyIds = await getCachedCompanyIds();
return new Date({name: name, companies: companyIds});
}
This will have a document like:
{
name: "TODAY'S DATE",
companies: ['5e2076236664640d22515f7b', '5e2076236664640d22515f7a']
}
If you want to populate the Date object with complete Company Information, You can use the populate method present in mongoose which populates the complete company information into the Date Object.
https://mongoosejs.com/docs/populate.html

Answer 3

I solved it:
router.route('/add').post((req, res) => {
const name = req.body.name;
Company.find().then(companies => {
const newDate = new Date({ name, companies });
newDate
.save()
.then(() => res.json('Date added!'))
.catch(err => res.status(400).json('Error: ' + err));
});
});