Authorization Module

This devon4ng Angular module adds rights-based authorization to your Angular app. Eager to see how it works? Go to a Stackblitz demo.

Installation

$ npm install @devon4ng/authorization --save

Or you can use yarn:

$ yarn add @devon4ng/authorization

To install the correct vesion for your Angular project please refer to the @devon4ng/authorization versions available.

Usage

Thisdevon4ng Authorization Module mainly focuses on protecting your routes so that they can only be accessed by authorized users (having specific rights).

1. Configure the router

The starting point when setting up this devon4ng Authorization Module is Angular router with routes configured. So let's configure the router first - if you haven't done it yet :), e.g.:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { Dialog1Component } from './components/dialog1.component';
import { Dialog2Component } from './components/dialog2.component';
import { Dialog3Component } from './components/dialog3.component';

const routes: Routes = [
  {
    path: 'dialog1',
    component: Dialog1Component,
  },
  {
    path: 'dialog2',
    component: Dialog2Component,
  },
  {
    path: 'dialog3',
    component: Dialog3Component,
  },
  { path: '', pathMatch: 'full', redirectTo: '/dialog1' },
];

@NgModule({
  declarations: [AppComponent, Dialog1Component, Dialog2Component, Dialog3Component],
  imports: [BrowserModule, RouterModule.forRoot(routes)],
  bootstrap: [AppComponent],
})
export class AppModule {}

2. Import DevonfwAuthorizationModule.forRoot():

Similarly to the RouterModule you have to import DevonfwAuthorizationModule.forRoot() in the root @NgModule of your application.

import {DevonfwAuthorizationModule} from '@devon4ng/authorization';

const routes = ...

@NgModule({
  imports: [
    ...
    RouterModule.forRoot(routes),
    DevonfwAuthorizationModule.forRoot()
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

3. Configure rights needed to access your routes:

import { AuthorizedRoutes } from '@devon4ng/authorization';

enum Right {
  User,
  Admin,
}

const routes: AuthorizedRoutes<Right> = [
  {
    path: 'dialog1',
    component: Dialog1Component,
    permitAll: true,
  },
  {
    path: 'dialog2',
    component: Dialog2Component,
    authorizeForRight: Right.User,
  },
  {
    path: 'dialog3',
    component: Dialog3Component,
    authorizeForRight: Right.Admin,
  },
  { path: '', pathMatch: 'full', redirectTo: '/dialog1' },
];

Please note that in the above code we replaced the type Routes with the AuthorizedRoutes imported from @devon4ng/authorization. In addition to Routes' properties, the AuthorizedRoutes type provides:

• the permitAll property which, if set to true, makes a route public
• the authorizeForRight property which makes a route accessible only for users having the right provided as value
• the authorizeForRightsOf property which makes a route accessible only for users having all the rights provided as an array

4. Set the AuthorizationGuard on your routes:

In order for the router to protect your routes (according to the configuration provided above) you need to set the AuthorizationGuard on your routes (more on router guards here). The easiest way to do it is to make use of the addAuthorizationGuards function provided by the DevonfwAuthorizationModule:

import {DevonfwAuthorizationModule, addAuthorizationGuards} from '@devon4ng/authorization';

const routes = ...

@NgModule({
  imports: [
    ...
    RouterModule.forRoot(routes),
    DevonfwAuthorizationModule.forRoot()
  ],
  bootstrap: [AppComponent]
})
export class AppModule {
  constructor(router: Router) {
    addAuthorizationGuards(router);
  }
}

The addAuthorizationGuards function traverses the route configuration and sets the AuthorizationGuard on those routes having the path and component properties set.

If you need more control over on which routes the AuthorizationGuard is set, you can:

• pass a callback function to addAuthorizationGuards (as the 2nd argument):

// add guards to routes having paths and components provided, but having no children
addAuthorizationGuards(router, (route) => route.path != null && route.component && route.children == null);

• set the AuthorizationGuard manually, in which case you don't need addAuthorizationGuards anymore:

import { AuthorizedRoutes, AuthorizationGuard } from '@devon4ng/authorization';

enum Right {
  User,
  Admin,
}

const routes: AuthorizedRoutes<Right> = [
  {
    path: 'dialog1',
    component: Dialog1Component,
    authorizeForRight: Right.User,
    canActivate: [AuthorizationGuard],
  },
  {
    path: 'dialog2',
    component: Dialog2Component,
    permitAll: true,
    canActivate: [AuthorizationGuard],
  },
  { path: '', pathMatch: 'full', redirectTo: '/dialog1' },
];

4. Provide your IsAuthorized service:

The last piece of the puzzle is to provide a service which can be called by the AuthorizationGuard to find out if the current user is authorized for given rights. The DevonfwAuthorizationModule only provides a dummy service authorizing for any rights requested (AuthorizedForAnyRight).

Let's implement our simple AuthorizationService:

import { IsAuthorized } from '@devon4ng/authorization';
import { Observable, of } from 'rxjs';
import { Injectable } from '@angular/core';

// moved here from the AppModule to avoid a circular dependency
export enum Right {
  User,
  Admin,
}

@Injectable()
export class AuthorizationService implements IsAuthorized<Right> {
  private userRights = [Right.User]; // get the actual rights from your (authorization) server

  isAuthorizedForRightsOf(requiredRights: Right[]): Observable<boolean> {
    if (requiredRights && requiredRights.length > 0) {
      return of(this.userHasAllRightsOf(requiredRights));
    }
    return of(true); // when no required rights...
  }

  private userHasAllRightsOf(requiredRights: Right[]) {
    return requiredRights.reduce(
      (isAuthorized, requiredRight) =>
        isAuthorized ? (this.userRights ? this.userRights.includes(requiredRight) : false) : false,
      true
    );
  }
}

Please note that in real-life scenarios you would request the user rights from your server and cache them for the lifetime of your user session.

Now let's replace the DevonfwAuthorizationModule's dummy implementation with the one implemented above:

import {isAuthorizedInjectionToken} from '@devon4ng/authorization';

@NgModule({
  imports: [
    ...
    RouterModule.forRoot(routes),
    DevonfwAuthorizationModule.forRoot()
  ],
  providers: [{provide: isAuthorizedInjectionToken, useClass: AuthorizationService}]
  bootstrap: [AppComponent]
})
export class AppModule {}

5. Enjoy :)

Now you can try it out! Assuming the DevonfwAuthorizationModule was set up like described above you should be able to access both /dialog1 (because it is configured as a public route) and /dialog2 (because in the AuthorizationService we set user rights to Right.User). Access to /dialog3 will be denied: you will stay at the current route. This is not all about user friendliness :) To change this behavior you can configure the DevonfwAuthorizationModule to navigate to some route when the authorization check fails:

import {DevonfwAuthorizationModule, addAuthorizationGuards} from '@devon4ng/authorization';

const routes: AuthorizedRoutes<Right> = [
  ...
  {
    path: 'access-denied',
    component: AccessDeniedComponent,
    permitAll: true
  }
];

@NgModule({
  imports: [
    ...
    RouterModule.forRoot(routes),
    DevonfwAuthorizationModule.forRoot({urlOnAuthorizationFailure: '/access-denied'})
  ],
  bootstrap: [AppComponent]
})
export class AppModule {
  ...
}

The fully working demo is available on Github and Stackblitz.