import {
  AuthenticateFn,
  AuthenticationBindings,
  AUTHENTICATION_STRATEGY_NOT_FOUND,
  USER_PROFILE_NOT_FOUND,
} from '@loopback/authentication';
export class MySequence implements SequenceHandler {
  constructor(
    // - enable jwt auth -
    // inject the auth action
    @inject(AuthenticationBindings.AUTH_ACTION)
    protected authenticateRequest: AuthenticateFn,
  ) {}

  async handle(context: RequestContext) {
    try {
      const {request, response} = context;
      const route = this.findRoute(request);
      // - enable jwt auth -
      // call authentication action
      await this.authenticateRequest(request);

      const args = await this.parseParams(request, route);
      const result = await this.invoke(route, args);
      this.send(response, result);
    } catch (error) {
      // - enable jwt auth -
      // improve the error check
      if (
        error.code === AUTHENTICATION_STRATEGY_NOT_FOUND ||
        error.code === USER_PROFILE_NOT_FOUND
      ) {
        Object.assign(error, {statusCode: 401 /* Unauthorized */});
      }
      this.reject(context, error);
    }
  }
}

import {AuthenticationComponent} from '@loopback/authentication';
import {
  JWTAuthenticationComponent,
  RefreshTokenServiceBindings,
  SECURITY_SCHEME_SPEC,
} from '@loopback/authentication-jwt';

export class TestApplication extends BootMixin(
  ServiceMixin(RepositoryMixin(RestApplication)),
) {
  constructor(options: ApplicationConfig = {}) {
    super(options);

    // Set up the custom sequence
    this.sequence(MySequence);

    // Set up default home page
    this.static('/', path.join(__dirname, '../public'));

    // - enable jwt auth -
    // Mount authentication system
    this.component(AuthenticationComponent);
    // Mount jwt component
    this.component(JWTAuthenticationComponent);
    // Bind datasource for user
    this.dataSource(DbDataSource, UserServiceBindings.DATASOURCE_NAME);
    // Bind datasource for refresh token
    this.dataSource(DbDataSource, RefreshTokenServiceBindings.DATASOURCE_NAME);

    this.component(RestExplorerComponent);
    this.projectRoot = __dirname;
    // Customize @loopback/boot Booter Conventions here
    this.bootOptions = {};
  }
}

All the jwt authentication related code are marked with comment "- enable jwt auth -", you can search for it to find all the related code you need to enable the entire jwt authentication in a LoopBack 4 application.

Adding Endpoint in Controller

After mounting the component, you can call token and user services to perform login, then decorate endpoints with @authentication('jwt') to inject the logged in user's profile.

This module contains an example application in the fixtures folder. It has a controller with endpoints /login, /refreshlogin, /refresh and /whoAmI.

Before using the below snippet do not forget to inject below repositories and bindings in your controller's constructor

    @inject(TokenServiceBindings.TOKEN_SERVICE)
    public jwtService: TokenService,
    @inject(UserServiceBindings.USER_SERVICE)
    public userService: UserService<User, Credentials>,
    @inject(SecurityBindings.USER, {optional: true})
    private user: UserProfile,
    @inject(UserServiceBindings.USER_REPOSITORY)
    public userRepository: UserRepository,
    @inject(RefreshTokenServiceBindings.REFRESH_TOKEN_SERVICE)
    public refreshService: RefreshTokenService,

The code snippet for login function:

async login(
    @requestBody(CredentialsRequestBody) credentials: Credentials,
  ): Promise<{token: string}> {
    // ensure the user exists, and the password is correct
    const user = await this.userService.verifyCredentials(credentials);

    // convert a User object into a UserProfile object (reduced set of properties)
    const userProfile = this.userService.convertToUserProfile(user);

    // create a JSON Web Token based on the user profile
    const token = await this.jwtService.generateToken(userProfile);

    return {token};
  }

The code snippet for whoAmI function:

@authenticate('jwt')
  async whoAmI(): Promise<string> {
    return this.user[securityId];
  }

Endpoints with refresh token

To add refresh token mechanism in your app, you can follow below example code at the endpoint.

1. To generate refresh token : to generate the refresh token and access token when user logins to your app with provided credentials.

 async refreshLogin(
    @requestBody(CredentialsRequestBody) credentials: Credentials,
  ): Promise<TokenObject> {
    // ensure the user exists, and the password is correct
    const user = await this.userService.verifyCredentials(credentials);
    // convert a User object into a UserProfile object (reduced set of properties)
    const userProfile: UserProfile = this.userService.convertToUserProfile(
      user,
    );
    const accessToken = await this.jwtService.generateToken(userProfile);
    const tokens = await this.refreshService.generateToken(
      userProfile,
      accessToken,
    );
    return tokens;
  }

2. To refresh the token: to generate the access token by the refresh token obtained from the the last login endpoint.

  async refresh(
    @requestBody(RefreshGrantRequestBody) refreshGrant: RefreshGrant,
  ): Promise<TokenObject> {
    return this.refreshService.refreshToken(refreshGrant.refreshToken);
  }

The complete file is in user.controller.ts

Customization

As a prototype implementation this module provides basic functionalities in each service. You can customize and re-bind any element provided in the component with your own one.

Replacing the User model is a bit more complicated because it's not injected but imported directly in related files. The sub-section covers the steps to provide your own User model and repository.

Customizing User

1. Create your own user model and repository by running the lb4 model and lb4 repository commands.

2. The user service requires the user model and repository, to provide your own ones, you can create a custom UserService and bind it to UserServiceBindings.USER_SERVICE. Take a look at the default user service for an example of UserService implementation.

   For convenience, here is the code in user.service.ts. You can replace the User and UserRepository with MyUser, MyUserRepository:

   Check The Code

   import {UserService} from '@loopback/authentication';
   import {repository} from '@loopback/repository';
   import {HttpErrors} from '@loopback/rest';
   import {securityId, UserProfile} from '@loopback/security';
   import {compare} from 'bcryptjs';
   // User --> MyUser
   import {MyUser} from '../models';
   // UserRepository --> MyUserRepository
   import {MyUserRepository} from '../repositories';
   
   export type Credentials = {
     email: string;
     password: string;
   };
   
   // User --> MyUser
   export class CustomUserService implements UserService<MyUser, Credentials> {
     constructor(
       // UserRepository --> MyUserRepository
       @repository(MyUserRepository) public userRepository: MyUserRepository,
     ) {}
   
     // User --> MyUser
     async verifyCredentials(credentials: Credentials): Promise<MyUser> {
       const invalidCredentialsError = 'Invalid email or password.';
   
       const foundUser = await this.userRepository.findOne({
         where: {email: credentials.email},
       });
       if (!foundUser) {
         throw new HttpErrors.Unauthorized(invalidCredentialsError);
       }
   
       const credentialsFound = await this.userRepository.findCredentials(
         foundUser.id,
       );
       if (!credentialsFound) {
         throw new HttpErrors.Unauthorized(invalidCredentialsError);
       }
   
       const passwordMatched = await compare(
         credentials.password,
         credentialsFound.password,
       );
   
       if (!passwordMatched) {
         throw new HttpErrors.Unauthorized(invalidCredentialsError);
       }
   
       return foundUser;
     }
   
     // User --> MyUser
     convertToUserProfile(user: MyUser): UserProfile {
       return {
         [securityId]: user.id.toString(),
         name: user.username,
         id: user.id,
         email: user.email,
       };
     }
   }

3. Bind MyUserRepository (and MyUserCredentialsRepository if you create your own as well) to the corresponding key in your application.ts:

   import {CustomUserService} from './services/custom-user-service';
   import {MyUserRepository, MyUserCredentialsRepository} from './repositories';
   import {UserServiceBindings} from '@loopback/authentication-jwt';
   
   export class TestApplication extends BootMixin(
     ServiceMixin(RepositoryMixin(RestApplication)),
   ) {
     constructor(options: ApplicationConfig = {}) {
       super(options);
       // ...other setup
       this.component(JWTAuthenticationComponent);
       // Bind datasource
       this.dataSource(DbDataSource, UserServiceBindings.DATASOURCE_NAME);
       // Bind user service
       this.bind(UserServiceBindings.USER_SERVICE).toClass(CustomUserService),
       // Bind user and credentials repository
       this.bind(UserServiceBindings.USER_REPOSITORY).toClass(
         MyUserRepository,
       ),
       this.bind(UserServiceBindings.USER_CREDENTIALS_REPOSITORY).toClass(
         MyUserCredentialsRepository,
       ),
     }
   }

Extra configurations

1. To change the token secret in your application.ts

  // for jwt access token
  this.bind(TokenServiceBindings.TOKEN_SECRET).to("<yourSecret>");
  // for refresh token
  this.bind(RefreshTokenServiceBindings.TOKEN_SECRET).to("<yourSecret>");

2. To change token expiration. to learn more about expiration time here at Ziet/ms

  // for jwt access token expiration
    this.bind(TokenServiceBindings.TOKEN_EXPIRES_IN).to("<Expiration Time in sec>");
  // for refresh token expiration
    this.bind(RefreshTokenServiceBindings.TOKEN_EXPIRES_IN).to("<Expiration Time in sec>");

Future Work

The security specification is currently manually added in the application file. The next step is to create an enhancer in the component to automatically bind the spec when app starts.

Contributions

• Guidelines
• Join the team

Tests

Run npm test from the root folder.

Contributors

See all contributors.

License

MIT