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Angular Login with Session Authentication

Kapil Panchal - May 13, 2021

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Angular Login with Session Authentication

Introduction


In this article, we'll look at how to handle the login process with Session Authentication. We'll verify if the user is logged in or not, and if he is not, then the route will simply be blocked.

Let’s go through the following Angular principles for better understanding.s

 

Angular Routing module

Manage the user authentication permission for the Angular path.

 

Angular Auth Guard

This Angular function helps a lot when it comes to handling authentication. This is an interface that instructs the router whether or not to enable navigation to a specific route. We're using the 'canActivate' guard form in this case.

 

Angular localStorage

In an Angular program, there are three ways to store data on the client-side.

  1. Memory
  2. Session storage
  3. Local Storage.

Planning to hire Angular programmer for your next project?

We're using localStorage in this case, which saves data in the client browser. It can only be used in a modern browser. When the window is closed or reopened while in session storage, the data is retained; however, when the tab is closed, the data will be lost. It's easy to create a new Angular project create a new Angular project using a command. Given is the localStorage syntax which simply helps you to save up to 10MB of data in the browser.

Using the below command, create a new Angular project.

npm install bootstrap

Add the following line to the src/styles.css file after installation:

@import '~bootstrap/dist/css/bootstrap.min.css'; 

Build two components, one for login and one for the dashboard.

Create a service called auth.

Make a new user interface for logging in.

Using the command lines below, create a new guard called auth.

The Angular route guard, which can tell the router whether or not to enable navigation to a requested route, is referred to as Angular guard.

ng g component login

ng g component dashboard

ng g service services/auth //Build a service in the Services folder.

ng g interface interfaces/login //In the interfaces folder, build a new interface.

ng g guard guards/auth //Build a new guard in the Guards folder.

In the Login interfaces, add two properties.

Login.ts

 
export class ILogin {      
  userid: string;    
  password: string;    
}  
                

Now navigate to guards/Auth.guard.ts. Import the @angular/router package's 'canActivate' interface.

Auth.guard.ts

 
  import { Injectable } from '@angular/core';      
  import { ActivatedRouteSnapshot, RouterStateSnapshot, CanActivate, Router } from '@angular/router';      
  import { Observable } from 'rxjs';      
  @Injectable({      
     providedIn: 'root'      
  })      
  export class AuthGuard implements CanActivate {      
     constructor(private router: Router) { }      
     canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): boolean {      
        if (this.isLoggedIn()) {      
        return true;      
        }      
        // navigate to login page as user is not authenticated      
     this.router.navigate(['/login']);      
  return false;      
  }      
  public isLoggedIn(): boolean {      
     let status = false;      
     if (localStorage.getItem('isLoggedIn') == "true") {      
        status = true;      
     }
       else {      
        status = false;      
        }      
     return status;      
     }    
  }    

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Import the AuthGuard module into the app.module.ts format.

import { AuthGuard } from './guards/auth.guard'; 

Then, from the @angular/forms package, import ReactiveFormsModule and FormsModule into this file.

Our app.module.ts file should now look like this.

import { BrowserModule } from '@angular/platform-browser';    
import { NgModule } from '@angular/core';    
import { AppRoutingModule } from './app-routing.module';    
import { AppComponent } from './app.component';    
import { LoginComponent } from './login/login.component';    
import { DashboardComponent } from './dashboard/dashboard.component';    
import { AuthGuard } from './guards/auth.guard';    
import { FormsModule, ReactiveFormsModule } from '@angular/forms';    
    
@NgModule({    
   declarations: [    
   AppComponent,    
   LoginComponent,    
   DashboardComponent    
],    
imports: [    
   BrowserModule,    
   AppRoutingModule,    
   FormsModule,    
   ReactiveFormsModule    
],    
   providers: [AuthGuard],    
   bootstrap: [AppComponent]    
})    
export class AppModule { }    
                
 

Now edit the app-routing.modue.ts file to include login and dashboard routes. To verify user authentication, add the ‘canActivate' attribute here. It will redirect to the login page if the user is not allowed.

import { NgModule } from '@angular/core';  
import { Routes, RouterModule } from '@angular/router';  
import { LoginComponent } from './login/login.component';  
import { DashboardComponent } from './dashboard/dashboard.component'; 
import { AuthGuard } from './guards/auth.guard';  
 
  
const routes: Routes = [  
   { path: 'login', component: LoginComponent },  
   { path: 'dashboard', component: DashboardComponent, canActivate : [AuthGuard] }];  
@NgModule({  
   imports: [RouterModule.forRoot(routes)],  
   exports: [RouterModule]  
})  
export class AppRoutingModule { }  
                

In the app.component.html file, add the HTML code below.

The path of the URL is stored in routerLink, and routeLinkActive adds the class active to the selected menu. According to the route URL, will determine which View to show.

Import the ILogin interface into the auth.service.ts file.

import { ILogin } from 'src/app/interfaces/login'; 
                

Within this service class, add a Logout() method.

import { Injectable } from '@angular/core';    
import { ILogin } from '../interfaces/login';    
    
@Injectable({    
   providedIn: 'root'    
})    
export class AuthService {    
   constructor() { }    
   logout() :void {    
   localStorage.setItem('isLoggedIn','false');    
   localStorage.removeItem('token');    
   }    
}   
                

Now import Router from the @angular/router package into the login.component.ts module. Within this file, import the login interface and the AuthService.

import { Router } from '@angular/router';  
import { ILogin } from 'src/app/interfaces/login';  
import { AuthService } from '../services/auth.service' 
                

Also, import the @angular/forms package's FormBuilder, FormGroup, Validators.

import { FormBuilder, FormGroup, Validators } from '@angular/forms'; 
                

Inside the function Object() { [native code] }, create three instances: router, service, and formBuilder.

  constructor(  
  private formBuilder : FormBuilder,  
  private router : Router,  
  private authService : AuthService  
) { }
                

Set default parameters for a new variable modal as the ILogin interface.

model: ILogin = { userid: "admnin", password: "admin@123" }  
                

Make a loginForm variable with the FormGroup sort. The message is a string, and the returnURL is also a string.

loginForm: FormGroup;  
message: string;  
returnUrl: string;  

Build a new formGroup within the ngOnInit() method and apply the necessary validation to both properties.

 

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ngOnInit() {  
  this.loginForm = this.formBuilder.group({  
    userid: ['', Validators.required],  
    password: ['', Validators.required]  
  });  
  this.returnUrl = '/dashboard';  
  this.authService.logout();  
}  

Add a get method to make it easier to access the form.

get f() { return this.loginForm.controls; }  

Inside this class, add the Login() method.

login() {  
  if (this.loginForm.invalid) {  
    return;  
  }  
  else {  
    if (this.f.userid.value == this.model.userid && this.f.password.value == this.model.password) {  
      console.log("Login successful");  
      //this.authService.authLogin(this.model);  
      localStorage.setItem('isLoggedIn', "true");  
      localStorage.setItem('token', this.f.userid.value);  
      this.router.navigate([this.returnUrl]);  
    }  
    else {  
      this.message = "Please check your userid and password";  
    }  
  }  
} 
                

As a result, login.component.ts would look something like this:

import { Component, OnInit } from '@angular/core';  
import { Router } from '@angular/router';  
import { ILogin } from 'src/app/interfaces/login';  
import { AuthService } from '../services/auth.service'  
import { FormBuilder, FormGroup, Validators } from '@angular/forms';  
@Component({  
   selector: 'app-login',  
   templateUrl: './login.component.html',  
   styleUrls: ['./login.component.css']  
   })  
export class LoginComponent implements OnInit {  
   model: ILogin = { userid: "admnin", password: "admin@123" }  6
   loginForm: FormGroup;  
   message: string;  
   returnUrl: string;  
   constructor(  
      private formBuilder: FormBuilder,  
      private router: Router,  
      private authService: AuthService  
   ) { }  
   ngOnInit() {  
      this.loginForm = this.formBuilder.group({  
         userid: ['', Validators.required],  
         password: ['', Validators.required]  
      });  
   this.returnUrl = '/dashboard';  
   this.authService.logout();  
   }  
// convenience getter for easy access to form fields  
get f() { return this.loginForm.controls; }  
login() {  
  
   // stop here if form is invalid  
   if (this.loginForm.invalid) {  
      return;  
   }  
   else {  
      if (this.f.userid.value == this.model.userid && this.f.password.value == this.model.password) {  
      console.log("Login successful");  
      //this.authService.authLogin(this.model);  
      localStorage.setItem('isLoggedIn', "true");  
      localStorage.setItem('token', this.f.userid.value);  
      this.router.navigate([this.returnUrl]);  
      }  
   else {  
      this.message = "Please check your userid and password";  
      }  
     }  
  }  
}  
                

Login.component.html

Log In

{{message}}

Userid is required
Password is required
/pre>

Dashboard.component.ts

Implement the logout() method inside this.ts format. This page will be inaccessible if the user is not authenticated, and the user will be directed to the login page.

import { Component, OnInit } from '@angular/core';  
import { Router } from '@angular/router';  
import { AuthService } from '../services/auth.service';  
@Component({  
  selector: 'app-dashboard',  
  templateUrl: './dashboard.component.html',  
  styleUrls: ['./dashboard.component.css']  
})  
export class DashboardComponent implements OnInit {  
  
  id: string;  
  constructor(private router: Router, private authService: AuthService) { }  
  ngOnInit() {  
    this.id = localStorage.getItem('token');  
    //console.log(this.id);  
  } 
  logout() {  
    console.log('logout');  
    this.authService.logout();  
    this.router.navigate(['/login']);  
  } 
} 
                

Dashboard.component.html

The logged user's id will be shown within id if the user is registered.

                
Welcome, {{id}} Logout

Conclusion

In this blog, we have learned Angular Login with Session Authentication. We can manage user authentication, route access, and the session variable using this method. If the user is not authenticated, we may use this Angular Guard method to prevent requested navigation.

Angular Login with Session Authentication Table of Content 1. Introduction 1.1. Angular Routing module 1.2. Angular Auth Guard 1.3. Angular localStorage 2. Conclusion Introduction In this article, we'll look at how to handle the login process with Session Authentication. We'll verify if the user is logged in or not, and if he is not, then the route will simply be blocked. Let’s go through the following Angular principles for better understanding.s   Angular Routing module Manage the user authentication permission for the Angular path.   Angular Auth Guard This Angular function helps a lot when it comes to handling authentication. This is an interface that instructs the router whether or not to enable navigation to a specific route. We're using the 'canActivate' guard form in this case.   Angular localStorage In an Angular program, there are three ways to store data on the client-side. Memory Session storage Local Storage. Planning to hire Angular programmer for your next project? Contact us We're using localStorage in this case, which saves data in the client browser. It can only be used in a modern browser. When the window is closed or reopened while in session storage, the data is retained; however, when the tab is closed, the data will be lost. It's easy to create a new Angular project create a new Angular project using a command. Given is the localStorage syntax which simply helps you to save up to 10MB of data in the browser. Using the below command, create a new Angular project. npm install bootstrap Add the following line to the src/styles.css file after installation: @import '~bootstrap/dist/css/bootstrap.min.css'; Build two components, one for login and one for the dashboard. Create a service called auth. Make a new user interface for logging in. Using the command lines below, create a new guard called auth. The Angular route guard, which can tell the router whether or not to enable navigation to a requested route, is referred to as Angular guard. ng g component login ng g component dashboard ng g service services/auth //Build a service in the Services folder. ng g interface interfaces/login //In the interfaces folder, build a new interface. ng g guard guards/auth //Build a new guard in the Guards folder. In the Login interfaces, add two properties. Login.ts   export class ILogin { userid: string; password: string; } Now navigate to guards/Auth.guard.ts. Import the @angular/router package's 'canActivate' interface. Auth.guard.ts   import { Injectable } from '@angular/core'; import { ActivatedRouteSnapshot, RouterStateSnapshot, CanActivate, Router } from '@angular/router'; import { Observable } from 'rxjs'; @Injectable({ providedIn: 'root' }) export class AuthGuard implements CanActivate { constructor(private router: Router) { } canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): boolean { if (this.isLoggedIn()) { return true; } // navigate to login page as user is not authenticated this.router.navigate(['/login']); return false; } public isLoggedIn(): boolean { let status = false; if (localStorage.getItem('isLoggedIn') == "true") { status = true; } else { status = false; } return status; } } Seeking to hire DOT NET Developers for your project? Contact us Import the AuthGuard module into the app.module.ts format. import { AuthGuard } from './guards/auth.guard'; Then, from the @angular/forms package, import ReactiveFormsModule and FormsModule into this file. Our app.module.ts file should now look like this. import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; import { AppRoutingModule } from './app-routing.module'; import { AppComponent } from './app.component'; import { LoginComponent } from './login/login.component'; import { DashboardComponent } from './dashboard/dashboard.component'; import { AuthGuard } from './guards/auth.guard'; import { FormsModule, ReactiveFormsModule } from '@angular/forms'; @NgModule({ declarations: [ AppComponent, LoginComponent, DashboardComponent ], imports: [ BrowserModule, AppRoutingModule, FormsModule, ReactiveFormsModule ], providers: [AuthGuard], bootstrap: [AppComponent] }) export class AppModule { } Read More: The Comprehensive Guide To Angular Performance Tuning   Now edit the app-routing.modue.ts file to include login and dashboard routes. To verify user authentication, add the ‘canActivate' attribute here. It will redirect to the login page if the user is not allowed. import { NgModule } from '@angular/core'; import { Routes, RouterModule } from '@angular/router'; import { LoginComponent } from './login/login.component'; import { DashboardComponent } from './dashboard/dashboard.component'; import { AuthGuard } from './guards/auth.guard'; const routes: Routes = [ { path: 'login', component: LoginComponent }, { path: 'dashboard', component: DashboardComponent, canActivate : [AuthGuard] }]; @NgModule({ imports: [RouterModule.forRoot(routes)], exports: [RouterModule] }) export class AppRoutingModule { } In the app.component.html file, add the HTML code below. Toggle navigation Angular Registration   Login  Dashboard  The path of the URL is stored in routerLink, and routeLinkActive adds the class active to the selected menu. According to the route URL, will determine which View to show. Import the ILogin interface into the auth.service.ts file. import { ILogin } from 'src/app/interfaces/login'; Within this service class, add a Logout() method. import { Injectable } from '@angular/core'; import { ILogin } from '../interfaces/login'; @Injectable({ providedIn: 'root' }) export class AuthService { constructor() { } logout() :void { localStorage.setItem('isLoggedIn','false'); localStorage.removeItem('token'); } } Now import Router from the @angular/router package into the login.component.ts module. Within this file, import the login interface and the AuthService. import { Router } from '@angular/router'; import { ILogin } from 'src/app/interfaces/login'; import { AuthService } from '../services/auth.service' Also, import the @angular/forms package's FormBuilder, FormGroup, Validators. import { FormBuilder, FormGroup, Validators } from '@angular/forms'; Inside the function Object() { [native code] }, create three instances: router, service, and formBuilder. constructor( private formBuilder : FormBuilder, private router : Router, private authService : AuthService ) { } Set default parameters for a new variable modal as the ILogin interface. model: ILogin = { userid: "admnin", password: "admin@123" } Make a loginForm variable with the FormGroup sort. The message is a string, and the returnURL is also a string. loginForm: FormGroup; message: string; returnUrl: string; Build a new formGroup within the ngOnInit() method and apply the necessary validation to both properties.   Looking for Trusted AngularJS Development Company ? Your Search ends here. Contact us   ngOnInit() { this.loginForm = this.formBuilder.group({ userid: ['', Validators.required], password: ['', Validators.required] }); this.returnUrl = '/dashboard'; this.authService.logout(); } Add a get method to make it easier to access the form. get f() { return this.loginForm.controls; } Inside this class, add the Login() method. login() { if (this.loginForm.invalid) { return; } else { if (this.f.userid.value == this.model.userid && this.f.password.value == this.model.password) { console.log("Login successful"); //this.authService.authLogin(this.model); localStorage.setItem('isLoggedIn', "true"); localStorage.setItem('token', this.f.userid.value); this.router.navigate([this.returnUrl]); } else { this.message = "Please check your userid and password"; } } } As a result, login.component.ts would look something like this: import { Component, OnInit } from '@angular/core'; import { Router } from '@angular/router'; import { ILogin } from 'src/app/interfaces/login'; import { AuthService } from '../services/auth.service' import { FormBuilder, FormGroup, Validators } from '@angular/forms'; @Component({ selector: 'app-login', templateUrl: './login.component.html', styleUrls: ['./login.component.css'] }) export class LoginComponent implements OnInit { model: ILogin = { userid: "admnin", password: "admin@123" } 6 loginForm: FormGroup; message: string; returnUrl: string; constructor( private formBuilder: FormBuilder, private router: Router, private authService: AuthService ) { } ngOnInit() { this.loginForm = this.formBuilder.group({ userid: ['', Validators.required], password: ['', Validators.required] }); this.returnUrl = '/dashboard'; this.authService.logout(); } // convenience getter for easy access to form fields get f() { return this.loginForm.controls; } login() { // stop here if form is invalid if (this.loginForm.invalid) { return; } else { if (this.f.userid.value == this.model.userid && this.f.password.value == this.model.password) { console.log("Login successful"); //this.authService.authLogin(this.model); localStorage.setItem('isLoggedIn', "true"); localStorage.setItem('token', this.f.userid.value); this.router.navigate([this.returnUrl]); } else { this.message = "Please check your userid and password"; } } } } Login.component.html Log In {{message}} Userid Userid is required Password Password is required Login /pre> Planning to hire Blockchain software developers ? Reach out us Dashboard.component.ts Implement the logout() method inside this.ts format. This page will be inaccessible if the user is not authenticated, and the user will be directed to the login page. import { Component, OnInit } from '@angular/core'; import { Router } from '@angular/router'; import { AuthService } from '../services/auth.service'; @Component({ selector: 'app-dashboard', templateUrl: './dashboard.component.html', styleUrls: ['./dashboard.component.css'] }) export class DashboardComponent implements OnInit { id: string; constructor(private router: Router, private authService: AuthService) { } ngOnInit() { this.id = localStorage.getItem('token'); //console.log(this.id); } logout() { console.log('logout'); this.authService.logout(); this.router.navigate(['/login']); } } Dashboard.component.html The logged user's id will be shown within id if the user is registered. Welcome, {{id}} Logout Conclusion In this blog, we have learned Angular Login with Session Authentication. We can manage user authentication, route access, and the session variable using this method. If the user is not authenticated, we may use this Angular Guard method to prevent requested navigation.

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