Angular 2 Authentication: Protecting Private Content

This article demonstrates how to add authentication to an Angular application, safeguarding specific sections from unauthorized access. It's part 5 of a SitePoint Angular 2 tutorial on building a CRUD app with the Angular CLI.

This tutorial builds upon previous parts, but you can start with the part-4 code provided at //m.sbmmt.com/link/92e7f4b2ddd224859b3f38aa9378f949. The relevant code for this part is tagged as part-5.

Key Concepts:

This section uses Angular 2 and JSON Web Tokens (JWTs) for client-side session management. A backend (using json-server and body-parser) handles authentication requests and validates tokens. Dedicated Angular services (AuthService and SessionService) manage authentication logic and session data. A SignInComponent features a reactive form for user authentication, and route guards (CanActivate) prevent unauthorized route access. The ApiService is configured to include JWTs in Authorization headers for secure API communication. Finally, a sign-out feature in TodosComponent allows users to end sessions.

Setup:

Ensure you have the latest Angular CLI:

npm install -g @angular/cli@latest

(Use npm uninstall -g @angular/cli angular-cli; npm cache clean; npm install -g @angular/cli@latest to remove a prior version).

Clone the repository, checkout part-4, and install dependencies:

git clone git@github.com:sitepoint-editors/angular-todo-app.git
cd angular-todo-app
git checkout part-4
npm install
ng serve

Access the app at http://localhost:4200.

Implementation:

This article covers setting up a backend for authentication, adding a sign-in method to ApiService, creating authentication and session services, building a SignInComponent, implementing a route guard, and sending user tokens in API requests.

The backend (json-server.js) handles sign-in requests and protects routes based on token validation. The ApiService includes a signIn method. The SessionService stores session data (token and user name). The SignInComponent uses a reactive form for user input. A CanActivate guard protects routes, and ApiService sends tokens in request headers. A sign-out button is added to TodosComponent.

Authentication Strategy (JWTs):

The tutorial employs JWTs for client-side session management, contrasting with server-side session management using cookies. JWTs are stored client-side and sent to the server as needed.

Challenge:

The challenge involves persisting session data across browser refreshes using sessionStorage or localStorage.

FAQ:

The article concludes with a FAQ section covering Angular 2 authentication, form validation, implementing user authentication, the role of Angular CLI, handling errors, testing, and using LoginRadius CLI.

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