Angular 12 + Node.js Express + PostgreSQL example: CRUD App

In this tutorial, I will show you how to build a full-stack (Angular 12 + Node.js + Express + PostgreSQL) example with a CRUD Application. The back-end server uses Node.js + Express for REST APIs, front-end side is an Angular App with HTTPClient.

Related Posts:
– Angular + Node.js Express: JWT Authentication & Authorization example
– Server side Pagination with Node.js and Angular
– File Upload using Angular and Node.js

Run both projects in one place:
How to Integrate Angular with Node.js Restful Services

Serverless with Firebase:
– Angular Firebase CRUD Realtime DB | AngularFireDatabase
– Angular Firestore CRUD example | AngularFireStore

Other versions:
– Angular 8 + Node.js Express + PostgreSQL example
– Angular 10 + Node.js Express + PostgreSQL example
– Angular 11 + Node.js Express + PostgreSQL example
– Angular 13 + Node.js Express + PostgreSQL example
– Angular 14 + Node.js Express + PostgreSQL example
– Angular 15 + Node.js Express + PostgreSQL example

Angular 12 + Node.js + Express + PostgreSQL example

We will build a full-stack Tutorial Application in that:

• Tutorial has id, title, description, published status.
• User can create, retrieve, update, delete Tutorials.
• There is a search box for finding Tutorials by title.

Here are screenshots of the example.

– Create a Tutorial:

– Retrieve all Tutorials:

– Click on Edit button to update a Tutorial:

On this Page, you can:

• change status to Published using Publish button
• delete the Tutorial using Delete button
• update the Tutorial details with Update button

If you want to implement Form Validation, please visit:
Angular 12 Form Validation example (Reactive Forms)

– Search Tutorials by title:

– Check PostgreSQL database:

Full-stack CRUD App Architecture

We’re gonna build the application with following architecture:

– Node.js Express exports REST APIs & interacts with PostgreSQL Database using Sequelize ORM.
– Angular Client sends HTTP Requests and retrieves HTTP Responses using HTTPClient, consume data on the components. Angular Router is used for navigating to pages.

Video

This is our Angular + Node.js PostgreSQL application demo and brief instruction, running with Express Rest Apis:

In the video, we use Angular 10, but the UI and logic are the same as this Angular version 12.

Node.js Express Back-end

Overview

These are APIs that Node.js Express App will export:

Project Structure

– db.config.js exports configuring parameters for PostgreSQL connection & Sequelize.
– Express web server in server.js where we configure CORS, initialize & run Express REST APIs.
– Next, we add configuration for PostgreSQL database in models/index.js, create Sequelize data model in models/tutorial.model.js.
– Tutorial controller in controllers.
– Routes for handling all CRUD operations (including custom finder) in tutorial.routes.js.

Create Node.js App

First, we create a folder:

$ mkdir nodejs-express-sequelize-postgresql
$ cd nodejs-express-sequelize-postgresql

Next, we initialize the Node.js App with a package.json file:

npm init

name: (nodejs-express-sequelize-postgresql) 
version: (1.0.0) 
description: Node.js Rest Apis with Express, Sequelize & PostgreSQL.
entry point: (index.js) server.js
test command: 
git repository: 
keywords: nodejs, express, sequelize, postgresql, rest, api
author: bezkoder
license: (ISC)

Is this ok? (yes) yes

We need to install necessary modules: express, sequelize, pg, pg-hstore.
Run the command:

npm install express sequelize pg pg-hstore cors --save

*pg for PostgreSQL and pg-hstore for converting data into the PostgreSQL hstore format.

Setup Express web server

In the root folder, let’s create a new server.js file:

const express = require("express");
const cors = require("cors");

const app = express();

var corsOptions = {
  origin: "http://localhost:8081"
};

app.use(cors(corsOptions));

// parse requests of content-type - application/json
app.use(express.json());

// parse requests of content-type - application/x-www-form-urlencoded
app.use(express.urlencoded({ extended: true }));

// simple route
app.get("/", (req, res) => {
  res.json({ message: "Welcome to bezkoder application." });
});

// set port, listen for requests
const PORT = process.env.PORT || 8080;
app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}.`);
});

What we do are:
– import express and cors modules:

• Express is for building the Rest apis
• cors provides Express middleware to enable CORS with various options.

– create an Express app, then add body-parser (json, urlencoded) and cors middlewares using app.use() method. Notice that we set origin: http://localhost:8081.
– define a GET route which is simple for test.
– listen on port 8080 for incoming requests.

Now let’s run the app with command: node server.js.
Open your browser with url http://localhost:8080/, you will see:

Yeah, the first step is done. We’re gonna work with Sequelize in the next section.

Configure PostgreSQL database & Sequelize

In the app folder, we create a separate config folder for configuration with db.config.js file like this:

module.exports = {
  HOST: "localhost",
  USER: "postgres",
  PASSWORD: "123",
  DB: "testdb",
  dialect: "postgres",
  pool: {
    max: 5,
    min: 0,
    acquire: 30000,
    idle: 10000
  }
};

First five parameters are for PostgreSQL connection.
pool is optional, it will be used for Sequelize connection pool configuration:

• max: maximum number of connection in pool
• min: minimum number of connection in pool
• idle: maximum time, in milliseconds, that a connection can be idle before being released
• acquire: maximum time, in milliseconds, that pool will try to get connection before throwing error

For more details, please visit API Reference for the Sequelize constructor.

Initialize Sequelize

We’re gonna initialize Sequelize in app/models folder that will contain model in the next step.

Now create app/models/index.js with the following code:

const dbConfig = require("../config/db.config.js");

const Sequelize = require("sequelize");
const sequelize = new Sequelize(dbConfig.DB, dbConfig.USER, dbConfig.PASSWORD, {
  host: dbConfig.HOST,
  dialect: dbConfig.dialect,
  operatorsAliases: false,

  pool: {
    max: dbConfig.pool.max,
    min: dbConfig.pool.min,
    acquire: dbConfig.pool.acquire,
    idle: dbConfig.pool.idle
  }
});

const db = {};

db.Sequelize = Sequelize;
db.sequelize = sequelize;

db.tutorials = require("./tutorial.model.js")(sequelize, Sequelize);

module.exports = db;

Don’t forget to call sync() method in server.js:

...
const app = express();
app.use(...);

const db = require("./app/models");
db.sequelize.sync();

...

In development, you may need to drop existing tables and re-sync database. Just use force: true as following code:

db.sequelize.sync({ force: true }).then(() => {
  console.log("Drop and re-sync db.");
});

Define the Sequelize Model

In models folder, create tutorial.model.js file like this:

module.exports = (sequelize, Sequelize) => {
  const Tutorial = sequelize.define("tutorial", {
    title: {
      type: Sequelize.STRING
    },
    description: {
      type: Sequelize.STRING
    },
    published: {
      type: Sequelize.BOOLEAN
    }
  });

  return Tutorial;
};

This Sequelize Model represents tutorials table in PostgreSQL database. These columns will be generated automatically: id, title, description, published, createdAt, updatedAt.

After initializing Sequelize, we don’t need to write CRUD functions, Sequelize supports all of them:

• create a new Tutorial: create(object)
• find a Tutorial by id: findByPk(id)
• get all Tutorials: findAll()
• update a Tutorial by id: update(data, where: { id: id })
• remove a Tutorial: destroy(where: { id: id })
• remove all Tutorials: destroy(where: {})
• find all Tutorials by title: findAll({ where: { title: ... } })

These functions will be used in our Controller.

We can improve the example by adding Comments for each Tutorial. It is the One-to-Many Relationship and I write a tutorial for this at:
Node.js Sequelize Associations: One-to-Many example

Or you can add Tags for each Tutorial and add Tutorials to Tag (Many-to-Many Relationship):
Node.js Sequelize Associations: Many-to-Many example

Create the Controller

Inside app/controllers folder, let’s create tutorial.controller.js with these CRUD functions:

• create
• findAll
• findOne
• update
• delete
• deleteAll
• findAllPublished

const db = require("../models");
const Tutorial = db.tutorials;
const Op = db.Sequelize.Op;

// Create and Save a new Tutorial
exports.create = (req, res) => {
  
};

// Retrieve all Tutorials from the database.
exports.findAll = (req, res) => {
  
};

// Find a single Tutorial with an id
exports.findOne = (req, res) => {
  
};

// Update a Tutorial by the id in the request
exports.update = (req, res) => {
  
};

// Delete a Tutorial with the specified id in the request
exports.delete = (req, res) => {
  
};

// Delete all Tutorials from the database.
exports.deleteAll = (req, res) => {
  
};

// Find all published Tutorials
exports.findAllPublished = (req, res) => {
  
};

You can continue with step by step to implement this Node.js Express App (with Github) in the post:
Node.js Express & PostgreSQL: CRUD Rest APIs example with Sequelize

Run the Node.js Express Server

Run our Node.js application with command: node server.js.

Angular 12 Front-end

Overview

– The App component is a container with router-outlet. It has navbar that links to routes paths via routerLink.

– TutorialsList component gets and displays Tutorials.
– TutorialDetails component has form for editing Tutorial’s details based on :id.
– AddTutorial component has form for submission new Tutorial.

– These Components call TutorialService methods which use Angular HTTPClient to make HTTP requests and receive responses.

Technology

• Angular 12
• Angular HttpClient
• Angular Router
• Bootstrap 4

Project Structure

– tutorial.model.ts exports the main class model: Tutorial.
– There are 3 components: tutorials-list, tutorial-details, add-tutorial.
– tutorial.service has methods for sending HTTP requests to the Apis.
– app-routing.module.ts defines routes for each component.
– app component contains router view and navigation bar.
– app.module.ts declares Angular components and import necessary modules.

Setup Angular 12 Project

Let’s open cmd and use Angular CLI to create a new Angular Project as following command:

ng new Angular12Crud
? Would you like to add Angular routing? Yes
? Which stylesheet format would you like to use? CSS

We also need to generate some Components and Services:

ng g s services/tutorial

ng g c components/add-tutorial
ng g c components/tutorial-details
ng g c components/tutorials-list

ng g class models/tutorial --type=model

Set up App Module

Open app.module.ts and import FormsModule, HttpClientModule:

...
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';

@NgModule({
  declarations: [ ... ],
  imports: [
    ...
    FormsModule,
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Define Routes for Angular AppRoutingModule

There are 3 main routes:
– /tutorials for tutorials-list component
– /tutorials/:id for tutorial-details component
– /add for add-tutorial component

app-routing.module.ts

import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { TutorialsListComponent } from './components/tutorials-list/tutorials-list.component';
import { TutorialDetailsComponent } from './components/tutorial-details/tutorial-details.component';
import { AddTutorialComponent } from './components/add-tutorial/add-tutorial.component';

const routes: Routes = [
  { path: '', redirectTo: 'tutorials', pathMatch: 'full' },
  { path: 'tutorials', component: TutorialsListComponent },
  { path: 'tutorials/:id', component: TutorialDetailsComponent },
  { path: 'add', component: AddTutorialComponent }
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

Define Model Class

Our main model class Tutorial will be exported in tutorial.model.ts with 4 fields:

• id
• title
• description
• published

models/tutorial.model.ts

export class Tutorial {
  id?: any;
  title?: string;
  description?: string;
  published?: boolean;
}

Create Data Service

This service will use Angular HttpClient to send HTTP requests.
You can see that its functions includes CRUD operations and finder method.

services/tutorial.service.ts

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';
import { Tutorial } from '../models/tutorial.model';

const baseUrl = 'http://localhost:8080/api/tutorials';

@Injectable({
  providedIn: 'root'
})
export class TutorialService {

  constructor(private http: HttpClient) { }

  getAll(): Observable<Tutorial[]> {
    return this.http.get<Tutorial[]>(baseUrl);
  }

  get(id: any): Observable<Tutorial> {
    return this.http.get(`${baseUrl}/${id}`);
  }

  create(data: any): Observable<any> {
    return this.http.post(baseUrl, data);
  }

  update(id: any, data: any): Observable<any> {
    return this.http.put(`${baseUrl}/${id}`, data);
  }

  delete(id: any): Observable<any> {
    return this.http.delete(`${baseUrl}/${id}`);
  }

  deleteAll(): Observable<any> {
    return this.http.delete(baseUrl);
  }

  findByTitle(title: any): Observable<Tutorial[]> {
    return this.http.get<Tutorial[]>(`${baseUrl}?title=${title}`);
  }
}

Create Angular Components

As you’ve known before, there are 3 components corresponding to 3 routes defined in AppRoutingModule.

• Add new Item Component
• List of items Component
• Item details Component

You can continue with step by step to implement this Angular App in the post:
Angular 12 CRUD Application example with Web API

Other versions:
– Angular 8 CRUD example with Web API
– Angular 10 CRUD example with Web API
– Angular 11 CRUD example with Web API
– Angular 13 CRUD example with Web API
– Angular 14 CRUD example with Web API
– Angular 15 CRUD example with Web API

Run the Angular 12 App

You can run this App with command: ng serve --port 8081.
If the process is successful, open Browser with Url: http://localhost:8081/ and check it.

Further Reading

• Express.js Routing
• https://www.npmjs.com/package/express
• https://www.npmjs.com/package/pg
• Tutorials and Guides for Sequelize v5
• Angular HttpClient
• Angular Template Syntax

Source Code

You can find Github source code for this tutorial at: Angular + Express Github

Conclusion

Now we have an overview of Angular 12 + Node.js Express + PostgreSQL example when building a full-stack CRUD App.

We also take a look at client-server architecture for REST API using Express & Sequelize ORM, as well as Angular 12 project structure for building a front-end app to make HTTP requests and consume responses.

Next tutorials show you more details about how to implement the system (with Github):
– Back-end

– Front-end:

• Using Angular 8
• Using Angular 10
• Using Angular 11
• Using Angular 12
• Using Angular 13
• Using Angular 14
• Using Angular 15

You will want to know how to run both projects in one place:
How to Integrate Angular with Node.js Restful Services

More Practice:
– Angular + Node.js: Authentication and Authorization example
– File Upload using Angular and Node.js
– Server side Pagination with Node.js and Angular

Serverless with Firebase:
– Angular Firebase CRUD Realtime DB | AngularFireDatabase
– Angular Firestore CRUD example | AngularFireStore

If you want to implement Form Validation, please visit:
Angular 12 Form Validation example (Reactive Forms)

Happy learning, see you again!