Ionic 4 JWT Authentication Tutorial: Using Angular HttpClient with Node & Express.js Server

Ionic 4 is the latest version of Ionic which is as of this writing in RC. In this tutorial, we'll be learning how to use Ionic 4 and Angular 7 to build a login & registration module for authenticating users. We'll learn about using Angular modules, services, forms (via FormsModule) and HTTP (via HttpClient) among other features.

We'll learn how to use HttpClient to send POST requests to a back-end authentication server created with Node and Express.js and the BehaviorSubject type of RxJS Observable to track the authentication state.

We'll learn how to use the Ionic Storage module for persisting JWT information returned from our Express.js server such as the access token and the expiration date.

Before your proceed, you need to make sure you have Node.js and NPM installed on your development machine. You should be able to install them by downloading the binaries for your system from the official website.

Now, let's get started!

Setting up Ionic CLI 4

Our first step is installing the Ionic CLI 4. Open your terminal and run this command:

$ npm install -g ionic

This will install the ionic package globally on your system. If you get any permission errors simply use sudo before your command. If you are in Windows, use a CMD prompt with administrator access.

Creating an Ionic 4 Project

Let's now proceed by creating an Ionic 4 project. Head back to your terminal and run the following command:

$ ionic start ionic-auth-demo blank --type=angular   

We use the --type to specify the type of the framework we want to use with Ionic. Starting with v4, Ionic is only a mobile UI library that can be used on top of Angular, Vue and React or simply plain JavaScript to build hybrid mobile apps or progressive web apps.

We use the blank template for generating a project which comes with one page called home.

A couple of questions will be asked by the CLI such as if you want to install Cordova and if you want to Install the free Ionic Appflow SDK and connect your app?. Answer those questions as you prefer because this won't affect our next steps in this tutorial.

Wait for the dependencies to be installed then navigate in your project's root folder and serve your application using these commands:

$ cd ionic-auth-demo 
$ ionic serve

You can access your mobile application using your web browser from the localhost:8100 address.

Creating an Angular Module

Modules are used to organize your application code. For the authentication feature in our application we'll create a module that encapsulates the service and pages that handle user authentication. In your terminal, run:

$ ionic generate module auth

The src/app/auth/auth.module.ts file will be created with the basic code for a module:

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';

@NgModule({
  declarations: [],
  imports: [
    CommonModule
  ]
})
export class AuthModule { }

Our auth module only imports the CommonModule which is a built in Angular module that exports all the basic Angular directives and pipes, such as [NgIf](https://angular.io/api/common/NgIf), [NgForOf](https://angular.io/api/common/NgForOf), [DecimalPipe](https://angular.io/api/common/DecimalPipe), and so on.

You need to import the auth module in the root application module of our Ionic 4 application. Open the src/app/app.module.ts file and import AuthModule then add it to the imports array:

import { AuthModule } from  './auth/auth.module';

@NgModule({
  declarations: [AppComponent],
  entryComponents: [],
  imports: [BrowserModule, IonicModule.forRoot(), AppRoutingModule,
    AuthModule
  ],
  providers: [
    StatusBar,
    SplashScreen,
    { provide: RouteReuseStrategy, useClass: IonicRouteStrategy }
  ],
  bootstrap: [AppComponent]
})
export class AppModule {}

Let's import other modules that are necessary for our application such as HttpClient for sending HTTP requests, FormsModule for working with forms and Ionic Storage module for working with local storage in Ionic apps.

Importing HttpClient

HttpClient is the official http client of Angular so we need to import it in our Ionic/Angular project. Open the src/app/auth/auth.module.ts file and import HttpClientModule:


import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { HttpClientModule } from '@angular/common/http';

@NgModule({
  declarations: [],
  imports: [
    CommonModule,
    HttpClientModule
  ]
})
export class AuthModule { }

That's all we need to import HttpClient in our authentication module.

Setting up Forms

Angular provides powerful APIs for working with forms either through the template-based forms or reactive forms. In this tutorial, we'll use template-based forms so we need to import FormsModule in our main application module. In the same src/app/auth/auth.module.ts file:


import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { HttpClientModule } from '@angular/common/http';
import { FormsModule } from '@angular/forms';

@NgModule({
  declarations: [],
  imports: [
    CommonModule,
    HttpClientModule,
    FormsModule
  ]
})
export class AuthModule { }

Setting up Ionic Storage Module

The Ionic team provides the Ionic Storage module that can be used to work with the browser's local storage in mobile devices but before we can use it in our application, we need to install it from npm and import it in our authentication module. Head back to your terminal and run the following command:

$ npm install --save @ionic/storage

As of this writing, ionic/storage v2.2.0 will be installed on your project.

Next, include IonicStorageModule.forRoot() in the imports array:


import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { HttpClientModule } from '@angular/common/http';
import { FormsModule } from '@angular/forms';

import { IonicStorageModule } from '@ionic/storage';

@NgModule({
  declarations: [],
  imports: [
    CommonModule,
    HttpClientModule,
    FormsModule,
    IonicStorageModule.forRoot()
  ]
})
export class AuthModule { }

Creating the Angular Authentication Service

After setting up the necessary modules for our project, let's now create an authentication service that encapsulates communication with the Express server via HttpClient. In your terminal, run:

$ ionic generate interface auth/user

This will generate a user interface in the src/app/auth/user.ts file. Open the file and update it accordingly:

export interface User {
    id: number;
    name: string;
    email: string;
    password: string;
}

Note: We prefixed the interface name by auth/ to tell the CLI to generate it inside the auth module.

Also, you need to generate an interface for the server response:

$ ionic generate interface auth/auth-response

Open the src/app/auth/auth-response.ts file and update it accordingly:

export interface AuthResponse {
    user: {
        id: number,
        name: string,
        email: string,
        access_token: string,
        expires_in: number
    }
}

This corresponds to the response that will be returned from the authentication server that we'll be creating in the next section with Node and Express.js.

Next, generate the service using:

$ ionic generate service auth/auth

Two src/app/auth/auth.service.ts and src/app/auth/auth.service.spec.ts (tests) files will be generated.

Note: We prefixed the service name by auth/ to tell the CLI to generate it inside the auth module.

Open the src/app/auth/auth.service.ts file and update it by following these steps. First add the necessary imports:

import { Injectable } from  '@angular/core';
import { HttpClient } from  '@angular/common/http';
import { tap } from  'rxjs/operators';
import { Observable, BehaviorSubject } from  'rxjs';

import { Storage } from  '@ionic/storage';
import { User } from  './user';
import { AuthResponse } from  './auth-response';

We import:

  • HttpClient for sending POST request to the Express server that handles authentication,
  • The tap() operator for performing side effects when subscribing to the observables returned by the HttpClient methods,
  • The Storage module for persisting the access token and expiration date in the local storage,
  • The Observable, BehaviorSubject APIs for working with asynchronous operations,
  • The User and AuthResponse interfaces.

This is the definition of BehaviorSubject:

One of the variants of Subjects is the BehaviorSubject, which has a notion of "the current value". It stores the latest value emitted to its consumers, and whenever a new Observer subscribes, it will immediately receive the "current value" from the BehaviorSubject.

Next, declare these variables in the service class:

AUTH_SERVER_ADDRESS:  string  =  'http://localhost:3000';
authSubject  =  new  BehaviorSubject(false);

The AUTH_SERVER_ADDRESS holds the address of the Express authentication server and authSubject is a type of Observable that will be used to subscribe to the authentication state.

Next, inject HttpClient and Storage services via the service's constructor:

constructor(private  httpClient:  HttpClient, private  storage:  Storage) { }

Sending a POST Request with HttpClient for Registering Users

Next, add the register() method that will be used for registering users in the Express server:


  register(user: User): Observable<AuthResponse> {
    return this.httpClient.post<AuthResponse>(`${this.AUTH_SERVER_ADDRESS}/register`, user).pipe(
      tap(async (res:  AuthResponse ) => {

        if (res.user) {
          await this.storage.set("ACCESS_TOKEN", res.user.access_token);
          await this.storage.set("EXPIRES_IN", res.user.expires_in);
          this.authSubject.next(true);
        }
      })

    );
  }

We simply use the post() method to send a POST request to the /register endpoint exposed by our authentication server that will be running from the localhost:3000/ address. We'll be creating the server with Node and Express.js in the next section.

We use the pipe() function to chain multiple operators. In our case we want to perform a side effect for storing JWT information (the access token and expiration date) in the local storage so we use the tap() operator that's available from RxJS.

In the tap() operator we check if the response has a user object and we set persist the access token and expiration date with the ACCESS_TOKEN and EXPIRES_IN keys. Next, we emit a true value to our authSubject using the next() method.

Sending a POST Request with HttpClient for Authenticating Users

Next, add the login() method that will be used for authenticating users:


  login(user: User): Observable<AuthResponse> {
    return this.httpClient.post(`${this.AUTH_SERVER_ADDRESS}/login`, user).pipe(
      tap(async (res: AuthResponse) => {

        if (res.user) {
          await this.storage.set("ACCESS_TOKEN", res.user.access_token);
          await this.storage.set("EXPIRES_IN", res.user.expires_in);
          this.authSubject.next(true);
        }
      })
    );
  }

We send a POST request with HttpClient to the /login endpoint of our Express.js server that handles JWT authentication. Next, we perform a side effect using the pipe() method and tap() operator available from RxJS for persist the JWT access token and expiration date returned from the server.

Logging out Users

Next, add the logout() method that will be used for removing JWT authentication information from the local storage:

  async logout() {
    await this.storage.remove("ACCESS_TOKEN");
    await this.storage.remove("EXPIRES_IN");
    this.authSubject.next(false);
  }

We also emit a false value in the BehaviorSubject representing the authentication state.

Getting the Authentication State

Finally add the isLoggedIn() method that will be used for checking id the user is logged in or not:


  isLoggedIn() {
    return this.authSubject.asObservable();
  }

We simply return authSubject variable casted to an Observable using the asObservable() method. You can check if the user is logged in by subscribing to call of this method.

Creating Ionic Pages

Now that we've created the service for authenticating users. Let's create the user interface with Ionic 4 UI components.

Check out this second tutorial: Ionic 4 Tutorial: Build a Login & Register UI.

Creating and Running an Express.js Authentication Server

Let's create a authentication server that exposes two /register and /login endpoints using Node.js and Express.js and a bunch of other modules.

First, create a folder for the server code:

$ mkdir express-auth-demo

Navigate in the folder and create a package.json file:

$ npm init -y

Next, install the following dependencies:

$ npm install --save express body-parser sqlite3 bcryptjs jsonwebtoken cors

Next, create an index.js file and add the following code:

"use strict";
const  express  =  require('express');
const  bodyParser  =  require('body-parser');
const cors = require('cors')
const  sqlite3  =  require('sqlite3').verbose();
const  jwt  =  require('jsonwebtoken');
const  bcrypt  =  require('bcryptjs');

const SECRET_KEY = "secretkey23456";

const  app  =  express();
const  router  =  express.Router();
app.use(cors())

router.use(bodyParser.urlencoded({ extended:  false }));
router.use(bodyParser.json());
const database = new sqlite3.Database("./my.db");

const  createUsersTable  = () => {
    const  sqlQuery  =  `
        CREATE TABLE IF NOT EXISTS users (
        id integer PRIMARY KEY,
        name text,
        email text UNIQUE,
        password text)`;

    return  database.run(sqlQuery);
}

const  findUserByEmail  = (email, cb) => {
    return  database.get(`SELECT * FROM users WHERE email = ?`,[email], (err, row) => {
            cb(err, row)
    });
}

const  createUser  = (user, cb) => {
    return  database.run('INSERT INTO users (name, email, password) VALUES (?,?,?)',user, (err) => {
        cb(err)
    });
}

createUsersTable();

router.get('/', (req, res) => {
    res.status(200).send('This is an authentication server');
});

router.post('/register', (req, res) => {

    const  name  =  req.body.name;
    const  email  =  req.body.email;
    console.log(req.body);
    const  password  =  bcrypt.hashSync(req.body.password);

    createUser([name, email, password], (err)=>{
        if(err) return  res.status(500).send("Server error!");
        findUserByEmail(email, (err, user)=>{
            if (err) return  res.status(500).send('Server error!');  
            const  expiresIn  =  24  *  60  *  60;
            const  accessToken  =  jwt.sign({ id:  user.id }, SECRET_KEY, {
                expiresIn:  expiresIn
            });
            res.status(200).send({ "user":  user, "access_token":  accessToken, "expires_in":  expiresIn          
            });
        });
    });
});


router.post('/login', (req, res) => {
    const  email  =  req.body.email;
    const  password  =  req.body.password;
    findUserByEmail(email, (err, user)=>{
        if (err) return  res.status(500).send('Server error!');
        if (!user) return  res.status(404).send('User not found!');
        const  result  =  bcrypt.compareSync(password, user.password);
        if(!result) return  res.status(401).send('Password not valid!');

        const  expiresIn  =  24  *  60  *  60;
        const  accessToken  =  jwt.sign({ id:  user.id }, SECRET_KEY, {
            expiresIn:  expiresIn
        });
        res.status(200).send({ "user":  user, "access_token":  accessToken, "expires_in":  expiresIn});
    });
});

app.use(router);
const  port  =  process.env.PORT  ||  3000;
const  server  =  app.listen(port, () => {
    console.log('Server listening at http://localhost:'  +  port);
}); 

For more details about this code, check out Node Express JWT Authentication — jsonwebtoken and bcryptjs.

Next, add a start script in package.json:

"scripts": {
    "start": "node index.js"
},

You can now, run your authentication server using:

$ npm start

Your server will be running from http://localhost:3000.

You can use cURL to send POST requests to the authentication endpoints before creating the Ionic 4 UI. First run this command in a new terminal to register a user:

 curl -H "Content-Type: application/json" -d '{"email":"test@test.com","name":"test", "password":"test"}' http://localhost:3000/register

Next, run this command to login the user:

 curl -H "Content-Type: application/json" -d '{"email":"test@test.com", "password":"test"}' http://localhost:3000/login

Conclusion

In this tutorial, we've learned how to implement JWT authentication with Ionic 4, Angular 7 on the front-end and Node and Express.js in the back-end. We've seen how to send POST requests using HttpClient and how to persist values on the local storage using the Ionic Storage module.

Note: We also publish our tutorials on Medium and DEV.to. If you prefer reading in these platforms, you can follow us there to get our newest articles.

You can reach the author via Twitter:

About the author

Ahmed Bouchefra
is a web developer with 5+ years of experience and technical author with an engineering degree on software development. You can hire him with a click on the link above or contact him via his LinkedIn account. He authored technical content for the industry-leading websites such as SitePoint, Smashing, DigitalOcean, RealPython, freeCodeCamp, JScrambler, Pusher, and Auth0. He also co-authored various books about modern web development that you can find from Amazon or Leanpub


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