In this article, we will see how to build a REST API using Node/Express and Sequelize. Building REST API using Node/Express and Sequelize.
Recent Article on Node.js
Understanding Event Emitter in Node.js
Apache Kafka for Node.js Developers
we will be using Postgres database for this tutorial along with Sequelize. Sequelize is an ORM for Node.js and Relational databases such as MySQL,MSSQL,Postgres and SQLite.
Firstly, postgres and Node.js needs to be installed in your machine. Follow this instruction to install postgres and node.js on your machine.
Once postgres is installed, Start postgres server and you will see a dashboard like following
create a folder called node-sequelize and install express with the following command.
1npm init --yes2npm install express body-parser
After that, Install Sequelize and postgres with the following command.
1npm install sequelize sequelize-cli pg pg-hstore
sequelize-cli can be installed in two ways. one is globally and another one is locally to the project. Here, we install locally to the project.
Initialize the Sequelize using the following command
1node_modules/.bin/sequelize init
Since, we installed sequelize locally to the project, we need to refer by using node_modules/.bin/sequelize
Above command will create a bunch of folders such as config,migrations and models
config.json will contain three environments such as development,test and production. Change the config.json to postgres database in development environment
1"development": {2 "username": "postgres",3 "password": null4 "database": "testdb",5 "host": "127.0.0.1",6 "port" : 5432,7 "dialect": "postgres"8 }
In models folder, create files such as post.js and user.js and add the following code.
1//POST Schema2module.exports = (sequelize, DataTypes) => {3 let Post = sequelize.define("Post", {4 title: DataTypes.STRING,5 })67 Post.associate = function(models) {8 Post.belongsTo(models.User, {9 onDelete: "CASCADE",10 foreignKey: "userId",11 })12 }1314 return Post15}
1//USER Schema2module.exports = (sequelize, DataTypes) => {3 let User = sequelize.define("User", {4 email: DataTypes.STRING,5 })67 User.associate = function(models) {8 User.hasMany(models.Post, {9 foreignKey: "userId",10 as: "posts",11 })12 }13 return User14}
A Hands-On Guidebook to Learn Cloud Native Web Development - From Zero To Production
consider a scenario , where user will have lots of posts and a post will belongs to user. In technical terms of database design, it is called as relationships. there are three types of relationship between two entities.they are,
To implement this concepts, we have Assocation in postgres sequelize.
Once you create a models, create files in migrations to create tables in database.
1//auser-migration.js2module.exports = {3 up: (queryInterface, Sequelize) =>4 queryInterface.createTable("Users", {5 id: {6 allowNull: false,7 autoIncrement: true,8 primaryKey: true,9 type: Sequelize.INTEGER,10 },11 email: {12 type: Sequelize.STRING,13 allowNull: false,14 },15 createdAt: {16 allowNull: false,17 type: Sequelize.DATE,18 },19 updatedAt: {20 allowNull: false,21 type: Sequelize.DATE,22 },23 }),24 down: (queryInterface /* , Sequelize */) => queryInterface.dropTable("Users"),25}
1//create-post.js2module.exports = {3 up: (queryInterface, Sequelize) =>4 queryInterface.createTable("Posts", {5 id: {6 allowNull: false,7 autoIncrement: true,8 primaryKey: true,9 type: Sequelize.INTEGER,10 },11 title: {12 type: Sequelize.STRING,13 allowNull: false,14 },15 userId: {16 type: Sequelize.INTEGER,17 onDelete: "CASCADE",18 references: {19 model: "Users",20 key: "id",21 as: "userId",22 },23 },24 createdAt: {25 allowNull: false,26 type: Sequelize.DATE,27 },28 updatedAt: {29 allowNull: false,30 type: Sequelize.DATE,31 },32 }),33 down: (queryInterface /* , Sequelize */) => queryInterface.dropTable("Posts"),34}
Run the following command to migrate the tables to database
1node_modules/.bin/sequelize db:migrate
As a result,it will create tables in postgres database.
Firstly, create a folder called controller. In controller, create files user.js and post.js . basically, we are going to write API to create User and Post.
1//user.js2const User = require("../models").User3module.exports = {4 async getAllUsers(req, res) {5 try {6 const userCollection = await User.find({})78 res.status(201).send(userCollection)9 } catch (e) {10 console.log(e)1112 res.status(500).send(e)13 }14 },1516 async create(req, res) {17 try {18 const userCollection = await User.create({19 email: req.body.email,20 })2122 res.status(201).send(userCollection)23 } catch (e) {24 console.log(e)25 res.status(400).send(e)26 }27 },2829 async update(req, res) {30 try {31 const userCollection = await User.find({32 id: req.params.userId,33 })3435 if (userCollection) {36 const updatedUser = await User.update({37 id: req.body.email,38 })3940 res.status(201).send(updatedUser)41 } else {42 res.status(404).send("User Not Found")43 }44 } catch (e) {45 console.log(e)4647 res.status(500).send(e)48 }49 },50}
1//post.js2const Post = require("../models").Post3const User = require("../models").User45module.exports = {6 async getAllPostsOfUser(req, res) {7 try {8 const userCollection = await User.find({9 id: req.params.userId,10 })1112 if (userCollection) {13 const postCollection = await Post.find({14 userId: req.params.userId,15 })1617 res.status(201).send(postCollection)18 } else {19 re.status(404).send("User Not Found")20 }21 } catch (e) {22 console.log(e)23 res.status(500).send(e)24 }25 },2627 async createPost(req, res) {28 try {29 const post = await Post.create({30 title: req.body.title,31 userId: req.body.userId,32 })33 res.status(201).send(post)34 } catch (e) {35 console.log(e)36 res.status(400).send(e)37 }38 },3940 async update(req, res) {41 try {42 const postCollection = await Post.find({43 id: req.params.postId,44 })4546 if (postCollection) {47 const updatedPost = await postCollection.update({48 title: req.body.title,49 })5051 res.status(201).send(updatedPost)52 } else {53 res.status(404).send("Post Not Found")54 }55 } catch (e) {56 console.log(e)57 res.status(400).send(e)58 }59 },60}
In addition,import post.js and user.js in the controller index file.
create a folder called router and add the following code in index.js
1//index.js2const userController = require("../controller").user3const postController = require("../controller").post4module.exports = app => {5 app.get("/api", (req, res) => {6 res.status(200).send({7 data: "Welcome Node Sequlize API v1",8 })9 })1011 app.get("/api/users", userController.getAllUsers)1213 app.post("/api/user/create", userController.create)1415 app.put("/api/user/:userId", userController.update)1617 app.get("/api/:userId/posts", postController.getAllPostsOfUser)1819 app.post("/api/post/create", postController.createPost)2021 app.put("/api/:postId", postController.update)22}
Finally, index.js file will look like
1const express = require("express")2const bodyParser = require("body-parser")3const app = express()45app.use(bodyParser.json())6app.use(bodyParser.urlencoded({ extended: false }))78require("./server/routes")(app)910const PORT = 345611app.listen(PORT, () => {12 console.log(`Server is listening to port ${PORT}`)13})
Run the Application using the command
1node index.js
Complete Source can be found here
To sum up, we can Build REST API in Node/Express Application using Sequelize for Postgres database.
No spam, ever. Unsubscribe anytime.