Using guards to block login from logged users

Author: Bernardo-MG

src/app/app-routing.module.ts

@@ -1,13 +1,14 @@
 import { NgModule } from '@angular/core';
 import { RouterModule, Routes } from '@angular/router';
 import { AuthenticatedGuard } from './authentication/guard/authenticated.guard';
-  
+import { LoggedOutGuard } from './authentication/guard/logged-out.guard';
+
 const loginModule = () => import('@app/login/login.module').then(m => m.LoginModule);
 const dataModule = () => import('@app/data/data.module').then(m => m.DataModule);
 
 const routes: Routes = [
   { path: '', redirectTo: '/data', pathMatch: 'full' },
-  { path: 'login', loadChildren: loginModule },
+  { path: 'login', loadChildren: loginModule, canActivate: [LoggedOutGuard] },
   { path: 'data', loadChildren: dataModule, canActivate: [AuthenticatedGuard] }
 ];
 

src/app/authentication/guard/authenticated.guard.ts

@@ -1,5 +1,6 @@
 import { Injectable } from '@angular/core';
-import { ActivatedRouteSnapshot, CanActivate, Router, RouterStateSnapshot } from '@angular/router';
+import { ActivatedRouteSnapshot, CanActivate, Router, RouterStateSnapshot, UrlTree } from '@angular/router';
+import { Observable } from 'rxjs';
 import { AuthenticationService } from '../service/authentication.service';
 
 @Injectable({
@@ -14,7 +15,9 @@ export class AuthenticatedGuard implements CanActivate {
     private authenticationService: AuthenticationService
   ) { }
 
-  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
+  canActivate(
+    route: ActivatedRouteSnapshot,
+    state: RouterStateSnapshot): Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree {
     const logged = this.authenticationService.getUser().logged;
     let active;
 

src/app/authentication/guard/logged-out.guard.spec.ts

@@ -0,0 +1,16 @@
+import { TestBed } from '@angular/core/testing';
+
+import { LoggedOutGuard } from './logged-out.guard';
+
+describe('LoggedOutGuard', () => {
+  let guard: LoggedOutGuard;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({});
+    guard = TestBed.inject(LoggedOutGuard);
+  });
+
+  it('should be created', () => {
+    expect(guard).toBeTruthy();
+  });
+});

src/app/authentication/guard/logged-out.guard.ts

@@ -0,0 +1,37 @@
+import { Injectable } from '@angular/core';
+import { ActivatedRouteSnapshot, CanActivate, Router, RouterStateSnapshot, UrlTree } from '@angular/router';
+import { Observable } from 'rxjs';
+import { AuthenticationService } from '../service/authentication.service';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class LoggedOutGuard implements CanActivate {
+
+  private homeUrl = '/';
+
+  constructor(
+    private router: Router,
+    private authenticationService: AuthenticationService
+  ) { }
+
+  canActivate(
+    route: ActivatedRouteSnapshot,
+    state: RouterStateSnapshot): Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree {
+    const logged = this.authenticationService.getUser().logged;
+    let active;
+
+    if (logged) {
+      // Logged in
+      // Redirect to home
+      active = false;
+      this.router.navigate([this.homeUrl]);
+    } else {
+      // Not logged in
+      active = true;
+    }
+
+    return active;
+  }
+
+}

src/app/login/view/login-view/login-view.component.ts

@@ -1,4 +1,3 @@
-import { HttpErrorResponse } from '@angular/common/http';
 import { Component, OnInit } from '@angular/core';
 import { ActivatedRoute, Router } from '@angular/router';
 import { AuthenticationService } from '@app/authentication/service/authentication.service';
@@ -24,11 +23,6 @@ export class LoginViewComponent implements OnInit {
   ) { }
 
   ngOnInit() {
-    // redirect to home if already logged in
-    if (this.authenticationService.getUser().logged) {
-      this.router.navigate(['/']);
-    }
-
     // get return url from route parameters or default to '/'
     this.returnUrl = this.route.snapshot.queryParams['returnUrl'] || '/';
   }