mongodb one to many relationship using nodejs and express - node.js

Question

Its been a tough time for me trying to figure this out.
The problem I'm trying to solve is this:
I have USERS who has list of COMPANIES,
this COMPNAY has list of PROJECTS etc.
I'm trying to create a PROJECT under a COMPANY and a COMPANY under a USER using referencing.
This USER is going to be populated from form fields likewise COMPANY PROJECT
USERS SCHEMA
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
//============= User Schema============//
const userSchema = new Schema({
name: String,
email: String,
//referencing user's company/companies
company: [
{
type: mongoose.Schema.Types.ObjectId,
ref: 'company',
},
],
},{
timestamps: true
});
const Users = mongoose.model('user', userSchema);
module.exports = Users;
COMPANY SCHEMA
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
//======== Company schema ========//
const compSchema = new Schema({
company_name: String,
//referencing user schema
user: [
{
type: mongoose.Schema.Types.ObjectId,
ref: 'user',
},
],
//referencing projects
projects: [
{
type: mongoose.Schema.Types.ObjectId,
ref: 'project',
},
],
},{
timestamps: true
});
const Company = mongoose.model('company', compSchema);
module.exports = Company;
PROJECT SCHEMA
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
//PROJECT SCHEMA
const projectSchema = new Schema({
project_title: String,
//referencing company schema
company: [
{
type: mongoose.Schema.Types.ObjectId,
ref: 'company',
}
],
},{
timestamps: true
});
const Projects = mongoose.model('project', projectSchema);
module.exports = Projects;
CONTROLLERS
const Users = require('./userSchema');
const Company = require('./companySchema');
const Projects = require('./projectSchema');
//create user
exports.createUser = async (req, res) => {
const data = {
name: req.body.name,
email: req.body.email,
}
Users.create(data, (err, done) => {
if(err) return err;
res.json({UserData: done});
return;
});
}
exports.getAllUsers = async(req, res) => {
}
//create company
exports.createCompany = async (req, res) => {
const CompanyData = {
company_name: req.body.company_name,
}
Company.create(companyData, (err, done) => {
if(err) return err;
res.json({CompanyDetails: done});
return;
});
}
exports.getllCompany = async (req, res) => {
}
//create project
exports.createProject = async (req, res) => {
const projectData = {
project_title: req.body.project_title,
}
Projects.create(projectData, (err, done) => {
if(err) return err;
res.json({ProjectDetails: done});
return;
});
}
exports.getAllProjects = async (req, res) => {
}
I understand that populate can be used to push documents to children. Any assistance offered will be highly appreciated

Answer 1

Store reference
Firstly, while creating a Company inside createCompany controller, you should add user _id in users array like this:
const CompanyData = {
company_name: req.body.company_name,
users: [req.body.userId] // Lets assume, user _id is coming in request body
}
Company.create(companyData, (err, done) => {
// Your code
});
Then, when you create a Project, add _id of Company you just created, in createProject controller like this:
const projectData = {
project_title: req.body.project_title,
company: [req.body.comapnyId] // Again assuming, company _id is coming in request body
}
Projects.create(projectData, (err, done) => {
// Your code
});
Update reference
Also, as I see in your schemas, you are trying to keep it bidirectional, like user's _ids in company doc & company's _ids in user doc.
To achieve this, if you create a user, you should update the corresponding company with pushing(addToSet actually) new user _id in user array.
Example:
To create a user in controller, run two scripts synchronously one-by-one:
Create a user with company _id and other details.
const data = {
name: req.body.name,
email: req.body.email,
company: [req.body.companyId]
}
Users.create(data, (err, done) => {
// Your code
});
Update company doc(whose _id is saved in above user) with _id of newly created user.
const updateCompany = { "$addToSet": { user: user._id } }; // Get `user._id` from above synchronous script
Company.update({_id: req.body.companyId}, data, (err, done) => { // Updated filter
// Your code
});