loizenai

Posted on Mar 5, 2021

Mongoose One-to-Many Relationship Example

#mongoose #onetomany #node

https://loizenai.com/mongoose-one-to-many-relationship-example/

Tutorial: "Mongoose One-to-Many Relationship Example - Mongodb One-to-Many Relationship Example"

In the tutorial, we will show you how to develop One-to-Many related document with NodeJs/Express, MongoDB using Mongoose.

Objective - Mongoose One-to-Many Relationship Example

In the tutorial, we show how to develop One-to-Many related documents with NodeJS/Express, MongoDB. Project structure:


/nodejs-restapi-mongodb
    /app
        /config
            mongodb.config.js
        /controllers
            companies.controller.js
            products.controller.js
        /models
            company.model.js
            product.model.js
        /routes
            companies.routes.js
            products.routes.js
    /node_modules
    package.json
    server.js

For working with related documents, we use the ObjectId schema field.

CompanySchema:


const Product = require('../models/product.model.js');
const mongoose = require('mongoose'), Schema = mongoose.Schema;

const CompanySchema = mongoose.Schema({
    name: String,
    street: String,
    phone: String
});

module.exports = mongoose.model('Company', CompanySchema);

ProductSchema:


const Company = require('../models/company.model.js');
const mongoose = require('mongoose'), Schema = mongoose.Schema;

const ProductSchema = mongoose.Schema({
    code: String,
    name: String,
    details: String,
    company : { type: Schema.Types.ObjectId, ref: 'Company' }
});

module.exports = mongoose.model('Product', ProductSchema);

We can save the references to the related document by assigning the _id value:


  var apple = new Company({ 
    name: 'Apple', 
    street: 'Cupertino, CA 95014', 
    phone: '1-408-996-1010' 
  });

  apple.save(function (err) {
    if(err) return console.error(err.stack)
    
    console.log("Apple company is added")
    
    //Apple now exists, so lets create a Product
    var iphone7 = new Product({
      code: "A-123",
      name: "Iphone7",
      details: "Price: 649.00 USD & FREE shipping",
      company: apple._id
    });

    iphone7.save(function (err) {
      if(err) return console.error(err.stack)
      
      console.log("Iphone 7 is added")
    });
});

We use populate() to get the Company information in Product:


    Product.findOne({ name: req.params.productName })
    .populate('company')
    .exec(function (err, product) {
        if (err){
            // handle error here
            ...
        }
                    
        res.send(product);
    });

We didn't add our products to companies, how to get all products by a particular company?

One way, we create a references array field of products in CompanySchema as below:


const Product = require('../models/product.model.js');
const mongoose = require('mongoose'), Schema = mongoose.Schema;

const CompanySchema = mongoose.Schema({
    name: String,
    street: String,
    phone: String,
    products : [{ type: Schema.Types.ObjectId, ref: 'Product' }]
});

module.exports = mongoose.model('Company', CompanySchema);

BUT What is problem? - We have two places where the information relating companies and products needs to be maintained.

What is the better solution?

-> We get the _id of our company, then use find() to search for this in the company field across all products.


Product.find({ company : req.params.companyId })
.exec(function (err, products) {
    if (err){
        // handle error here
        ...
    }
                
    res.send(products);
});

Create a NodeJS/Express project - Mongoose One-to-Many Relationship Example

Following below guide:
Crud RestAPIs with NodeJS/Express, MongoDB using Mongoose

See dependencies in 'package.json' file:


  "dependencies": {
    "body-parser": "^1.18.2",
    "express": "^4.16.3",
    "mongoose": "^5.0.13",
    "npm": "^5.8.0"
  }

Create Mongoose Model Schema

CompanySchema:


const Product = require('../models/product.model.js');
const mongoose = require('mongoose'), Schema = mongoose.Schema;

const CompanySchema = mongoose.Schema({
    name: String,
    street: String,
    phone: String,
    products : [{ type: Schema.Types.ObjectId, ref: 'Product' }]
});

module.exports = mongoose.model('Company', CompanySchema);

ProductSchema :


const Company = require('../models/company.model.js');
const mongoose = require('mongoose'), Schema = mongoose.Schema;

const ProductSchema = mongoose.Schema({
    code: String,
    name: String,
    details: String,
    company : { type: Schema.Types.ObjectId, ref: 'Company' }
});

module.exports = mongoose.model('Product', ProductSchema);

Nodejs Express RestAPI Route - Mongoose One-to-Many Relationship Example

Company Routes :


module.exports = function(app) {

    var companies = require('../controllers/companies.controller.js')
    
    app.get('/api/companies/init', companies.init);
    app.get('/api/companies', companies.findAll);
}

Product Routes :


module.exports = function(app) {
    var products = require('../controllers/products.controller.js');
    
    app.get('/api/products', products.findAll);
            
    // Find a single Product by Name
    app.get('/api/products/:productName', products.findByName);
    
    // Find all Products of a Company
    app.get('/api/products/company/:companyId', products.findByCompanyId);
}

Nodejs Express RestAPI Controller

Company Controllers :


const Company = require('../models/company.model.js');
const Product = require('../models/product.model.js');

exports.init = (req, res) => {
  var apple = new Company({ 
    name: 'Apple', 
    street: 'Cupertino, CA 95014', 
    phone: '1-408-996-1010' 
  });

  apple.save(function (err) {
    if(err) return console.error(err.stack)
    
    console.log("Apple company is added")
    
    //Apple now exists, so lets create a Product
    var iphone7 = new Product({
      code: "A-123",
      name: "Iphone7",
      details: "Price: 649.00 USD & FREE shipping",
      company: apple._id
    });

    iphone7.save(function (err) {
      if(err) return console.error(err.stack)
      
      console.log("Iphone 7 is added")
    });
    
    var iPadPro = new Product({
      code: "A-456",
      name: "IPadPro",
      details: "Price: 417.67 USD & FREE shipping",
      company: apple._id
    });
    
    iPadPro.save(function(err){
        if(err) return console.error(err.stack)
        
        console.log("IPadPro is added");
    });
    
  });
  
  
  var samsung = new Company({ 
        name: 'Samsung', 
        street: 'Seocho District, Seoul, South Korea', 
        phone: '+82-2-2053-3000'
    });
  
  samsung.save(function(err){
    if(err) return console.error(err.stack)
    
    console.log("Samsung company is added")
    
    // Samsung now exists, so lets create a Product
    var galaxyJ7 = new Product({
      code: "S-012",
      name: "GalaxyJ7",
      details: "Price: 219.00 USD & FREE shipping",
      company: samsung._id  
    });
    
    galaxyJ7.save(function(err){
        if(err) return console.error(err.stack)
        console.log("GalaxyJ7 is added")
    });
    
    var galaxyTabA = new Product({
      code: "S-456",
      name: "GalaxyTabA",
      details: "Price: 299.99 USD & FREE shipping",
      company: samsung._id
    });
    
    galaxyTabA.save(function(err){
        if(err) return console.error(err.stack)
        console.log("GalaxyTabA is added")
    })
  });
  
  res.send("Done Initial Data!");
}

exports.findAll = (req, res) => {
    Company.find()
    .then(products => {
        res.send(products);
    }).catch(err => {
        res.status(500).send({
            message: err.message
        });
    });
};

Product Controllers :


const Company = require('../models/company.model.js');
const Product = require('../models/product.model.js');

exports.findAll = (req, res) => {
    
    Product.find()
    .then(products => {
        res.send(products);
    }).catch(err => {
        res.status(500).send({
            message: err.message
        });
    });
};

// Find a Products by Name
exports.findByName = (req, res) => {
    Product.findOne({ name: req.params.productName })
    .populate('company')
    .exec(function (err, product) {
        if (err){
            if(err.kind === 'ObjectId') {
                return res.status(404).send({
                    message: "Products not found with given name " + req.params.productName
                });                
            }
            return res.status(500).send({
                message: "Error retrieving Products with given Company Id " + req.params.productName
            });
        }
                    
        res.send(product);
    });
};

// Find all products by a CompanyId
exports.findByCompanyId = (req, res) => {
    Product.find({ company : req.params.companyId })
    .exec(function (err, products) {
        if (err){
            if(err.kind === 'ObjectId') {
                return res.status(404).send({
                    message: "Products not found with given Company Id " + req.params.companyId
                });                
            }
            return res.status(500).send({
                message: "Error retrieving Products with given Company Id " + req.params.companyId
            });
        }
                    
        res.send(products);
    });
};

Run & Check results - Mongoose One-to-Many Relationship Example

Run MongDB server by commandline:


\MongoDB\Server\3.6\bin>mongod.exe
2018-04-11T03:11:42.209+0700 I CONTROL  [initandlisten] MongoDB starting : pid=2432 port=27017 dbpath=C:\data\db\ 64-bit host=LOI-COMPUTER
2018-04-11T03:11:42.211+0700 I CONTROL  [initandlisten] targetMinOS: Windows 7/Windows Server 2008 R2
2018-04-11T03:11:42.212+0700 I CONTROL  [initandlisten] db version v3.6.3
2018-04-11T03:11:42.212+0700 I CONTROL  [initandlisten] git version: 9586e557d54ef70f9ca4b43c26892cd55257e1a5
2018-04-11T03:11:42.212+0700 I CONTROL  [initandlisten] OpenSSL version: OpenSSL 1.0.1u-fips  22 Sep 2016
2018-04-11T03:11:42.212+0700 I CONTROL  [initandlisten] allocator: tcmalloc

Run NodeJS/Express application:


\nodejs-restapi-mongodb>node server.js
App listening at http://:::8081
Successfully connected to MongoDB.

Initial data

-> localhost:8081/api/companies/init

[caption id="attachment_4820" align="alignnone" width="705"] Node.js Mongodb One-to-many Related Document Initial Data[/caption]

Get all Companies:

-> localhost:8081/api/companies

[caption id="attachment_4821" align="alignnone" width="452"] Nodejs Mongodb One-to-many Related Document Find All Company[/caption]

Get all Products

-> localhost:8081/api/products

[caption id="attachment_4822" align="alignnone" width="440"] Nodejs Mongodb One-to-many Related Document Find All Product[/caption]

Find Product by Name:

-> localhost:8081/api/product/Iphone7

[caption id="attachment_4823" align="alignnone" width="410"] Nodejs Mongodb One-to-Many Related Document Find Product By Name Polulate Company[/caption]

Find Products by Company Id:

-> localhost:8081/api/products/company/5acd590b203d8e1ac01cb184

[caption id="attachment_4824" align="alignnone" width="532"] Nodejs Mongodb One-to-many Related Document Find All Products By Company ID[/caption]

Reference Link: Mongoose Association
Sourcecode

Node.js-MongoDB-One-to-Many-Example

DEV Community

Mongoose One-to-Many Relationship Example

Objective - Mongoose One-to-Many Relationship Example

Create a NodeJS/Express project - Mongoose One-to-Many Relationship Example

Create Mongoose Model Schema

Nodejs Express RestAPI Route - Mongoose One-to-Many Relationship Example

Nodejs Express RestAPI Controller

Run & Check results - Mongoose One-to-Many Relationship Example

Read More

Sourcecode

Top comments (0)

Read next

The Last Event Loop Guide you will Ever Need

Free Chat with Gemini Pro

You're Installing Node.js Wrong. That's OK, Here Is How To Fix It 🙌

E-Commerce with React Node Mysql

Objective - Mongoose One-to-Many Relationship Example

One-to-Many related models - Mongoose One-to-Many Relationship Example

Create a NodeJS/Express project - Mongoose One-to-Many Relationship Example

Create Mongoose Model Schema

Nodejs Express RestAPI Route - Mongoose One-to-Many Relationship Example

Nodejs Express RestAPI Controller

Run & Check results - Mongoose One-to-Many Relationship Example

Read More

Sourcecode

Read next

The Last Event Loop Guide you will Ever Need

Free Chat with Gemini Pro

You're Installing Node.js Wrong. That's OK, Here Is How To Fix It 🙌

E-Commerce with React Node Mysql