mean stack

What is Angular?
• Angular is an open-source JavaScript framework for building both
mobile and desktop web applications.
• Angular is exclusively used to build Single Page Applications (SPA).
• Angular is completely rewritten and is not an upgrade to Angular 1.
• Developers prefer TypeScript to write Angular code. But other than
TypeScript, you can also write code using JavaScript (ES5 or
ECMAScript 5).
• Madewithangularjs.com
Features of Angular
1. Dependency Injection
2. Data Binding
3. Testing
4. Model view Controller
ANGULAR

Angular application setup:
To develop an application using Angular on a local system, you need to
set up a development environment that includes the installation of:
• Node.js (^12.20.2 || ^14.15.5 || ^16.10.0) and npm (min
version required 6.13.4)
• Angular CLI
• Visual Studio Code
Steps to install Angular CLI:
• Angular CLI can be installed using Node package manager using the
command shown below
D:> npm install -g @angular/cli
ANGULAR APPLICATION
SETUP

ANGULAR APPLICATION
SETUP
• Test successful installation of Angular CLI using the following
command
D:> ng v

ANGULAR APPLICATION
SETUP
• Angular CLI is a command-line interface tool to build Angular
applications. It makes application development faster and easier to
maintain.
• Using CLI, you can create projects, add files to them, and perform
development tasks such as testing, bundling, and deployment of
applications.
--pic---in mail
• To create an application in the Angular.
ng new MyApp

COMPONENTS AND MODULES
Components:
• A component is the basic building block of an Angular application
• It emphasize the separation of concerns and each part of the
Angular application can be written independently of one another.
• It is reusable
Modules:
• Modules in Angular are used to organize the application. It sets the
execution context of an Angular application.
• A module in Angular is a class with the @NgModule decorator
added to it.
• @NgModule metadata will contain the declarations of
components, pipes, directives, services that are to be used across
the application.
• Every Angular application should have one root module which is
loaded first to launch the application.
• Submodules should be configured in the root module.

COMPONENTS AND MODULES
Components:
• A component is the basic building block of an Angular application
• It emphasize the separation of concerns and each part of the
Angular application can be written independently of one another.
• It is reusable

COMPONENTS AND
MODULES
• To create a component ng generate component component_name

Executing Angular Application
Execute the application and check the output.
• Open terminal in Visual Studio Code IDE by selecting View Menu ->
Integrated Terminal.
• Type the following command to run the application ng serve --open

Elements of Template
Template
• Templates separate the view layer from the rest of the
framework.
• You can change the view layer without breaking the
application.
• Templates in Angular represents a view and its role is to
display data and change the data whenever an event occurs
• The default language for templates is HTML
The basic elements of template syntax:
•HTML
•Template Expressions
•Template Statements

Example:
hello.component.ts:
import { Component, OnInit } from '@angular/core';
@Component({
selector: 'app-hello',
templateUrl: './hello.component.html',
styleUrls: ['./hello.component.css']
})
export class HelloComponent implements OnInit {
courseName = "Angular";
constructor() { }
ngOnInit() {
}
changeName() {
this.courseName = "TypeScript";
}

Example:
hello.component.html:
<h1>Welcome</h1>
<h2>Course Name: {{ courseName }}</h2>
<p (click)="changeName()">Click here to change</p>

Change Detection
• Angular’s change detection system operates by comparing the
current and previous states of the application data.
• When there is a change in the data, the change detection
mechanism triggers a re-evaluation of the view, updating it with the
new data.
• Angular offers two modes of change detection: default and OnPush.
• Angular is very fast though it goes through all components from
top to bottom for every single event as it generates VM-friendly
code.
• Due to this, Angular can perform hundreds of thousands of checks
in a few milliseconds.

Structural Directives
• A Structural directive changes the DOM layout by adding and
removing DOM elements.
*directive-name = expression
• Angular has few built-in structural directives such as:
• ngIf
• ngFor
• ngSwitch
ngIf:ngIf directive renders components or elements conditionally
based on whether or not an expression is true or false.
Examlpe:
App.component.ts:
import { Component } from '@angular/core';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})

export class AppComponent {
isAuthenticated!: boolean;
submitted = false;
userName!: string;
onSubmit(name: string, password: string) {
this.submitted = true;
this.userName = name;
if (name === 'admin' && password === 'admin') {
this.isAuthenticated = true;
} else {
this.isAuthenticated = false;
}
}
}

app.component.html:
<div *ngIf="!submitted">
<form>
<label>User Name</label>
<input type="text" #username /><br /><br />
<label for="password">Password</label>
<input type="password" name="password" #password /><br/>
</form>
<button (click)="onSubmit(username.value,
password.value)">Login</button>
</div>
<div *ngIf="submitted">
<div *ngIf="isAuthenticated; else failureMsg">
<h4>Welcome {{ userName }}</h4>
</div>
<ng-template #failureMsg>
<h4>Invalid Login !!! Please try again...</h4>
</ng-template>
<button type="button" (click)="submitted =
false">Back</button>
</div>

• ngFor:ngFor directive is used to iterate over-collection of data i.e.,
arrays.
*ngFor = "expression"
Example:
App.component.ts:
@Component({
})
courses: any[] = [
{ id: 1, name: "TypeScript" },
{ id: 2, name: "Angular" },
{ id: 3, name: "Node JS" },
{ id: 1, name: "TypeScript" }
];
}

App.component.html:
<ul>
<li *ngFor="let course of courses; let i = index">
{{i}} - {{ course.name }}
</li>
</ul>
Output

• ngSwitch:ngSwitch adds or removes DOM trees when their
expressions match the switch expression. Its syntax is comprised of two
directives, an attribute directive, and a structural directive.
• It is very similar to a switch statement in JavaScript and other
programming languages.
Example:
App.component.ts:
@Component({
})
choice = 0;
nextChoice() {
this.choice++;
}
}

App.component.html:
<h4>
Current choice is {{ choice }}
</h4>
<div [ngSwitch]="choice">
<p *ngSwitchCase="1">First Choice</p>
<p *ngSwitchCase="2">Second Choice</p>
<p *ngSwitchCase="3">Third Choice</p>
<p *ngSwitchCase="2">Second Choice Again</p>
<p *ngSwitchDefault>Default Choice</p>
</div>
<div>
<button (click)="nextChoice()">
Next Choice
</button>
</div>

Custom Structural Directive
• You can create custom structural directives when there is no built-in
directive available for the required functionality.
• For example, when you want to manipulate the DOM in a particular
way which is different from how the built-in structural directives
manipulate.
Example:
Generate a directive called 'repeat' using the following command:
ng generate directive repeat
Repeat.directive.ts:
import { Directive, TemplateRef, ViewContainerRef, Input
} from '@angular/core';
@Directive({
selector: '[appRepeat]'
})

Custom Structural Directive
export class RepeatDirective {
constructor(private templateRef: TemplateRef<any>,
private viewContainer: ViewContainerRef) { }
@Input() set appRepeat(count: number) {
for (let i = 0; i < count; i++) {
this.viewContainer.createEmbeddedView(this.templat
eRef);
}
}
}
App.component.html:
<h3>Structural Directive</h3>
<p *appRepeat="5">I am being repeated...</p>
Output:

Attribute Directives
• Attribute directives change the appearance/behavior of a component/element.
• Following are built-in attribute directives:
• ngStyle
• ngClass
• ngStyle:This directive is used to modify a component/element’s style. You
can use the following syntax to set a single CSS style to the element which is
also known as style binding
[style.<cssproperty>] = "value“
Example:
App.component.ts:
@Component({
})
colorName = 'yellow';
color = 'red';
}

app.component.html:
<div [style.background-color]="colorName"
[style.color]="color">
Uses fixed yellow background
</div>
Output:

• ngClass:It allows you to dynamically set and change the CSS classes for a
given DOM element. Use the following syntax to set a single CSS class to the
element which is also known as class binding.
Example:
App.component.ts:
@Component({
})
isBordered = true;
}
App.compnnent.html:
<div [class.bordered]="isBordered">
Border {{ isBordered ? "ON" : "OFF" }}
</div>

App.component.css:
.bordered {
border: 1px dashed black;
background-color: #eee;
}
Output:

Custom Attribute Directive
• You can create a custom attribute directive when there is no built-in
directive available for the required functionality.
Example:
Generate a directive called 'message' using the following command
ng generate directive message
Message.directive.ts:
import { Directive, ElementRef, Renderer2, HostListener,
Input } from '@angular/core';
@Directive({
selector: '[appMessage]'
})
export class MessageDirective {
@Input('appMessage') message!: string;
constructor(private el: ElementRef, private renderer:
Renderer2) {
renderer.setStyle(el.nativeElement, 'cursor',
'pointer');}

@HostListener('click') onClick() {
this.el.nativeElement.innerHTML = this.message;
this.renderer.setStyle(this.el.nativeElement, 'color',
'red');
}
}
App.component.ts:
@Component({
})
myMessage="Hello, I am from attribute directive"
}

app.component.html:
<h3>Attribute Directive</h3>
<p [appMessage]="myMessage">Click Here</p>
App.component.css:
h3 {
color: #369;
font-family: Arial, Helvetica, sans-serif;
font-size: 250%;
}
p {
color: #ff0080;
font-size: 150%;
}

Property Binding
• Property Binding in Angular helps you set values for properties of HTML
elements or directives.
• To bind to an element's property, enclose it in square brackets, [], which
identifies the property as a target property.A target property is the DOM
property to which you want to assign a value.
Syntax: <img [src] = 'imageUrl' />
or
<img bind-src = 'imageUrl' />
• Here the component's imageUrl property is bound to the value to the image
element's property src.
• Interpolation can be used as an alternative to property binding. Property
binding is mostly used when it is required to set a non-string value.
Example:
app.component.ts
@Component({

Property Binding
})
imgUrl = 'assets/logo.png';
}
Inside src/assets and place a logo.png file inside it.
app.component.html
<img [src]='imgUrl’>
Output:

Attribute Binding
• Property binding will not work for a few elements/pure attributes like ARIA,
SVG, and COLSPAN. In such cases, you need to go for attribute binding.
• Attribute binding can be used to bind a component property to the attribute
directly
• Binding to the colspan attribute helps you to keep your tables
programmatically dynamic.
• Depending on the amount of data that your application populates a table with,
the number of columns that a row spans could change.
• Attribute binding syntax starts with prefix attr. followed by a dot sign and the
name of an attribute. And then set the attribute value to an expression.
<td [attr.colspan] = "2+3">Hello</td>
Example:
app.component.ts
@Component({
})

Attribute Binding
colspanValue = '2’;
}
app.component.html
<table border=1>
<tr>
<td [attr.colspan]="colspanValue"> First </td>
<td>Second</td>
</tr>
<tr>
<td>Third</td>
<td>Fourth</td>
<td>Fifth</td>
</tr>
</table>

Style and Event Binding
 Style binding is used to set inline styles. Syntax starts with prefix style,
followed by a dot and the name of a CSS style property.
Syntax: [style.styleproperty]
 User actions such as entering text in input boxes, picking items from lists,
button clicks may result in a flow of data in the opposite direction: from an
element to the component.
 Event binding syntax consists of a target event with ( ) on the left of an equal
sign and a template statement on the right.
Syntax: < element (event) = function() >
Example:
app.component.ts
@Component({
})

onSave($event: any){
console.log("Save button is clicked!", $event)
}
}
app.component.html
<h1 [style.color] = "'red'"
[style.text-align] = "'left'" >
Style Binding!!!
</h1>
<h2>Event Binding </h2>
<button (click)="onSave($event)">Save</button>

Output:

Built in Pipes
• Pipes provide a beautiful way of transforming the data inside templates, for
the purpose of display.
• Pipes in Angular take an expression value as an input and transform it into
the desired output before displaying it to the user.
• It provides a clean and structured code as you can reuse the pipes throughout
the application, while declaring each pipe just once.
Syntax: {{ expression | pipe }}
• Uppercase:This pipe converts the template expression into uppercase.
Syntax:{{ expression | uppercase }}
• Lowercase:This pipe converts the template expression into lowercase.
Syntax: {{ expression | lowercase }}
• Titlecase:This pipe converts the first character in each word of the given
expression into a capital letter.
Syntax: {{ expression | titlecase }}

Built in Pipes
Example:
app.component.ts
@Component({
styleUrls: ['./app.component.css']})
title = 'product details';
productCode = 'PROD_P001';
productName = 'Laptop';
}
app.component,html
<h3> {{ title | titlecase}} </h3>
<table style="text-align:left">
<tr>
<th> Product Code </th>
<td> {{ productCode | lowercase }} </td>
</tr>

Built in Pipes
<tr>
<th> Product Name </th>
<td> {{ productName | uppercase }} </td>
</tr>
</table>
Output:

Passing Parameters to Pipes
• A pipe can also have optional parameters to change the output. To pass
parameters, after a
• pipe name add a colon( : ) followed by the parameter value.
pipename : parametervalue
• This pipe displays a currency symbol before the expression. By default, it
displays the currency symbol $
{{ expression | currency:currencyCode:symbol:digitInfo:locale }}
Example:
app.component.ts:
@Component({
})

title = 'product details';
productCode = 'PROD_P001';
productName = 'Apple MPTT2 MacBook Pro';
productPrice = 217021;
purchaseDate = '1/17/2018';
productTax = '0.1';
productRating = 4.92;
}
app.component.html:
<h3> {{ title | titlecase}} </h3>
<table style="text-align:left">
<tr>
<th> Product Code </th>
<td> {{ productCode | slice:5:9 }} </td>
</tr>

<tr>
<th> Product Name </th>
<td> {{ productName | uppercase }} </td>
</tr>
<tr>
<th> Product Price </th>
<td> {{ productPrice | currency:
'INR':'symbol':'':'fr' }} </td>
</tr>
<tr>
<th> Purchase Date </th>
<td> {{ purchaseDate | date:'fullDate' |
lowercase}} </td>
</tr>
<tr>
<th> Product Tax </th>
<td> {{ productTax | percent : '.2' }} </td>
</tr>

<tr>
<th> Product Rating </th>
<td>{{ productRating | number:'1.3-5'}} </td>
</tr>
</table>
app.module.ts:
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-
browser';
import { AppRoutingModule } from './app-
routing.module';
import { AppComponent } from './app.component';
import { CoursesListComponent } from './courses-
list/courses-list.component';
@NgModule({
declarations: [
AppComponent,
],

imports: [
BrowserModule,
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }
Output:

Nested Components Basics
• Nested component is a component that is loaded into another component
• The component where another component is loaded onto is called a
container component/parent component.
• The root component is loaded in the index.html page using its selector
name.
• Similarly, to load one component into a parent component, use the
selector name of the component in the template i.e., the HTML page of
the container component.
• Example Program:
app.module.ts
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import { CourseListComponent } from './course-list/course-
list.component';

@NgModule({
declarations: [
AppComponent,
CourseListComponent,
],
imports: [
BrowserModule,
],
providers: [],
})
course-list.component.ts:
@Component({
selector: 'app-course-list',
templateUrl: './course-list.component.html',
styleUrls: ['./course-list.component.css']
})

export class CourseListComponent {
courses = [
{ courseId: 1, courseName: "Node JS" },
{ courseId: 2, courseName: "Typescript" },
{ courseId: 3, courseName: "Angular" },
{ courseId: 4, courseName: "React JS" }
];
}
course.component.html:
<table border="1">
<thead>
<tr>
<th>Course ID</th>
<th>Course Name</th>
</tr>
</thead>

<tbody>
<tr *ngFor="let course of courses">
<td>{{ course.courseId }}</td>
<td>{{ course.courseName }}</td>
</tr>
</tbody>
</table>
course-list.component.css:
tr{
text-align:center;
}
app.component.html:
<h2>Popular Courses</h2>
<button (click)="show = true">View Courses
list</button><br /><br />
<div *ngIf="show">
<app-course-list></app-course-list>
</div>

app.component.ts:
@Component({
})
show!: boolean;
title: any;
}
Output:

Passing data from Container
Component to Child Component
• Component communication is needed if data needs to be shared between
the components In order to pass data from container/parent component to
child component, @Input decorator can be used.
• A child component can use @Input decorator on any property type like
arrays, objects, etc. making it a data-bound input property.
• The parent component can pass value to the data-bound input property
when rendering the child within it.
• Program:
courses-list.component.ts:
import { Component, Input } from '@angular/core';
@Component({
})

• Component communication is needed if data needs to be shared between
the components In order to pass data from container/parent component to
child component, @Input decorator can be used.
• A child component can use @Input decorator on any property type like
arrays, objects, etc. making it a data-bound input property.
• The parent component can pass value to the data-bound input property
when rendering the child within it.
Program:
courses-list.component.ts:
import { Component, Input } from '@angular/core';
@Component({
})

export class CourseListComponent {
courses = [
{ courseId: 1, courseName: "Node JS" },
{ courseId: 2, courseName: "Typescript" },
{ courseId: 3, courseName: "Angular" },
{ courseId: 4, courseName: "React JS" }
];
course!: any[];
@Input() set cName(name: string) {
this.course = [];
for (var i = 0; i < this.courses.length; i++) {
if (this.courses[i].courseName === name) {
this.course.push(this.courses[i]);
}
}
}
}

course-list.component.html:
<table border="1">
<thead>
<tr>
<th>Course ID</th>
</tr>
</thead>
<tbody>
<td>{{c.courseId}}</td>
<td>{{c.courseName}}</td>
</tr>
</tbody>
</table>

app.component.html:
<h2>Course Details</h2>
Select a course to view
<select #course (change)="name = course.value">
<option value="Node JS">Node JS</option>
<option value="Typescript">Typescript</option>
<option value="Angular">Angular</option>
<option value="React JS">React JS</option></select
><br /><br />
<app-courses-list [cName]="name"></app-courses-list>
app.component.ts:
@Component({
styleUrls: ['./app.component.css'],
templateUrl: './app.component.html'
})

name!: string;
}
Output:

Passing data from Child Component
to ContainerComponent
• If a child component wants to send data to its parent component, then it must
create a property with @Output decorator.
• The only method for the child component to pass data to its parent
component is through events. The property must be of type EventEmitter.
Program:
course-list.compnent.ts
import { Component,OnInit, Input,Output, EventEmitter
} from '@angular/core';
@Component({
selector: 'app-courses-list',
styleUrls: ['./course-list.component.css'],
})
export class CoursesListComponent {
courses = [
{ courseId: 1, courseName: 'Node JS' },
{ courseId: 2, courseName: 'Typescript' },

{ courseId: 3, courseName: 'Angular' },
{ courseId: 4, courseName: 'React JS' },
];
registerEvent: any;
register(courseName:string){
this.registerEvent.emit(courseName);
}
}
course-list.component.html
<table border="1">
<thead>
<tr>
<th>Course ID</th>
<th></th>
</tr>
</thead>

<tbody>
<td>{{ course.courseId }}</td>
<td>{{ course.courseName }}</td>
<td><button
(click)="register(course.courseName)">Register</button
></td>
</tr>
</tbody>
</table>
app.component.html
<h2>Courses List</h2>
<app-courses-list
(registerEvent)="courseReg($event)"></app-courses-
list>
<br /><br />
<div *ngIf="message">{{ message }}</div>

app.component.ts
@Component({
})
message!: string;
courseReg(courseName: string) {
this.message = `Your registration for
${courseName} is successful`;
}
}

Output:

Shadow DOM
• Shadow DOM is a web components standard by W3C.
• It enables encapsulation for DOM tree and styles. Shadow DOM hides DOM
logic behind other elements and confines styles only for that
component.ViewEncapsulation.ShadowDOM enables Angular to use the
browser's native Shadow DOM implementation.
• Angular doesn’t use shadow DOM in ViewEncapsulation.None.
• All the styles defined in a component is applied to the entire document. i.e., a
component can overwrite another component’s styles. This is an unscoped
strategy.
Program:
ViewEncapsulation.ShadowDOM:
Create a component first using ng generate component first

Shadow DOM
First.component.css:
.cmp {
padding: 6px;
margin: 6px;
border: blue 2px solid;
}
First.component.html:
<div class="cmp">First Component</div>
Now generate another component with name Second using ng generate second

Shadow DOM
Second.component.css
.cmp {
border: green 2px solid;
padding: 6px;
margin: 6px;
}
Second.component.html
<div class="cmp">Second Component</div>
Second.component.ts
import { Component, ViewEncapsulation } from
'@angular/core';
@Component({
selector: 'app-second',
templateUrl: './second.component.html',
styleUrls: ['./second.component.css'],
encapsulation: ViewEncapsulation.ShadowDom
})
export class SecondComponent {}

Shadow DOM
App.component.css
.cmp {
padding: 8px;
margin: 6px;
border: 2px solid red;
}
App.component.html
<h3>CSS Encapsulation with Angular</h3>
<div class="cmp">
App Component
<app-first></app-first>
<app-second></app-second>
</div>

Shadow DOM
Output:
ViewEncapsulation.None
App.component.ts:
'@angular/core';
@Component({
encapsulation: ViewEncapsulation.None
})
export class AppComponent {}

Shadow DOM
Second.component.ts:
'@angular/core';
@Component({
selector: 'app-second',
templateUrl: './second.component.html',
styleUrls: ['./second.component.css'],
encapsulation: ViewEncapsulation.None
})
export class SecondComponent {
}
Output:

Component Life Cycle
• A component has a life cycle that is managed by Angular.
• It includes creating a component, rendering it, creating and rendering its
child components, checks when its data-bound properties change, and
destroy it before removing it from the DOM.
• Angular has some methods/hooks which provide visibility into these key
life moments of a component and the ability to act when they occur.
ngOnChanges – It gets invoked when Angular sets data-bound input property
i.e., the property attached with @Input(). This will be invoked whenever input
property changes its value
ngOnInit – It gets invoked when Angular initializes the directive or
component
ngDoCheck - It will be invoked for every change detection in the application
ngAfterContentInit – It gets invoked after Angular projects content into its
view
ngAfterContentChecked – It gets invoked after Angular checks the bindings
of the content it projected into its view

Program:
app.component.ts:
import { Component, OnInit, DoCheck,
AfterContentInit, AfterContentChecked,AfterViewInit,
AfterViewChecked,OnDestroy } from '@angular/core';
@Component({
---------------
})
export class AppComponent implements OnInit, DoCheck,
AfterContentInit, AfterContentChecked,
AfterViewInit, AfterViewChecked,
OnDestroy {
data = 'Angular';
ngOnInit() {
console.log('Init');
}

ngDoCheck(): void {
console.log('Change detected');
}
ngAfterContentInit(): void {
console.log('After content init');
}
ngAfterContentChecked(): void {
console.log('After content checked');
}
ngAfterViewInit(): void {
console.log('After view init');
}
ngAfterViewChecked(): void {
console.log('After view checked');
}
ngOnDestroy(): void {
console.log('Destroy'); }
}

app.component.html:
<div>
<h1>I'm a container component</h1>
<input type="text" [(ngModel)]="data" />
<app-child [title]="data"></app-child>
</div>
Create child component using the command ng generate component child.
child.component.ts:
import { Component, OnChanges, Input }
from'@angular/core';
@Component({
-------------})
export class ChildComponent implements OnChanges {
@Input() title!: string;
ngOnChanges(changes: any): void {
console.log('changes in child:' +
JSON.stringify(changes));
} }

child.component.html:
<h2>Child Component</h2>
<h2>{{title}}</h2>
app.module.ts:
import { NgModule } from '@angular/core’;
--------------
import { FormsModule } from '@angular/forms’;
--------------------------
imports: [
BrowserModule,
AppRoutingModule,
FormsModule
],
providers: [],
bootstrap: [AppComponent],
})

Template Driven Forms
• Template-driven forms are the forms that are created using Angular template
syntax. In template-driven form, data binding, validation, etc., will be written
in the template itself.
• create a component called CourseFormComponent using the following
command
• D:>ng generate component courseForm
Program:
course.ts:
export class Course {
constructor(
public courseId: number,
public courseName: string,
public duration: string
) { }
}

course-form.component.ts:
import { Course } from './course’;
-----------
export class CourseFormComponent {
course = new Course(1, 'Angular', '5 days');
submitted = false;
onSubmit() { this.submitted = true; }}
Install Boostrap
PS D:...form> npm install bootstrap@3.3.7 --save
angular.json :
"styles": [
"styles.css",
"./node_modules/bootstrap/dist/css/bootstrap.min.css"
],

course-form.component.html :
<div class="container">
<div [hidden]="submitted">
<h1>Course Form</h1>
<form (ngSubmit)="onSubmit()" #courseForm="ngForm">
<div class="form-group">
<label for="id">Course Id</label>
<input type="text" class="form-control"
required [(ngModel)]="course.courseId" name="id"
#id="ngModel">
<div [hidden]="id.valid || id.pristine"
class="alert alert-danger">
Course Id is required
</div></div> <div class="form-group">
<label for="name">Course Name</label>
required [(ngModel)]="course.courseName" name="name"
#name="ngModel">
-------------------------------

<button type="submit" class="btn btn-default"
[disabled]="!courseForm.form.valid">Submit</button>
<button type="button" class="btn btn-default"
(click)="courseForm.reset()">New Course</button>
</form>
</div>
<div [hidden]="!submitted">
<h2>You submitted the following:</h2>
<div class="row">
<div class="col-xs-3">Course ID</div>
<div class="col-xs-9 pull-left">{{
course.courseId }}</div>
</div><div class="row">
<div class="col-xs-3">Course Name</div>
<div class="col-xs-9 pull-left">{{
course.courseName }}</div>
<br><button class="btn btn-default"
(click)="submitted=false">Edit</button>
</div></div>

course-form.component.css:
input.ng-valid[required] {
border-left: 5px solid #42A948; /* green */
}
input.ng-dirty.ng-invalid:not(form) {
border-left: 5px solid #a94442; /* red */
}
app.component.html:
<app-course-form></app-course-form>
app.module.ts:
---------------------------

imports: [
BrowserModule,
FormsModule
],
providers: [],
})
Output:

Model Driven Forms or
Reactive Forms
• In reactive forms, you can control the form completely from the component
class and hence you will get direct, explicit access to the underlying forms
object model.
• Hence, reactive forms are also known as 'model-driven forms'. As reactive
forms are more robust and scalable, they are more suitable for creating all kind
of forms in an application, irrespective of the size of form.
app.module.ts:
import { ReactiveFormsModule } from '@angular/forms’;
--------------------
import { RegistrationFormComponent } from
'./registration-form/registration-form.component';
imports: [
BrowserModule,
ReactiveFormsModule
],
----------------------
})export class AppModule { }

Reactive Forms
Command:ng generate component RegistrationForm
Install Bootstrap:
Command: npm install bootstrap@3.3.7 --save
registration-form.component.ts:
import { FormBuilder, FormGroup, Validators } from
'@angular/forms’;
------------------------
export class RegistrationFormComponent implements
OnInit {
registerForm!: FormGroup;
submitted!:boolean;

Reactive Forms
constructor(private formBuilder: FormBuilder) { }
ngOnInit() {
this.registerForm = this.formBuilder.group({
firstName: ['', Validators.required],
lastName: ['', Validators.required],
address: this.formBuilder.group({
street: [],
zip: [],
city: []
})
});
}
}
registration-form.component.html:
<h1>Registration Form</h1>
<form [formGroup]="registerForm">

Reactive Forms
<label>First Name</label>
formControlName="firstName">
----------------------------------------
<label>Last Name</label>
formControlName="lastName">
----------------------
<fieldset formGroupName="address">
<legend>Address:</legend>
<label>Street</label>
formControlName="street">
<label>Zip</label>

Reactive Forms
formControlName="zip">
<label>City</label>
formControlName="city">
</fieldset>
</div>
<button type="submit" class="btn btn-primary"
(click)="submitted=true">Submit</button>
</form>
<br/>
<h3> Employee Details </h3>
<p>First Name: {{
registerForm.get('firstName')?.value }} </p>

Reactive Forms
<p> Last Name: {{ registerForm.get('lastName')?.value
}} </p>
<p> Street: {{
registerForm.get('address.street')?.value }}</p>
<p> Zip: {{
registerForm.get('address.zip')?.value }} </p>
<p> City: {{
registerForm.get('address.city')?.value }}</p>
</div>
</div>
registration-form.component.css:
.ng-valid[required] {
border-left: 5px solid #42A948; /* green */
}
.ng-invalid:not(form) {
border-left: 5px solid #a94442; /* red */ }

Reactive Forms
app.component.html:
<app-registration-form></app-registration-form>
Output:

Custom Validators in
Reactive Forms
 Custom validation can be applied to form controls of a Reactive Form in
Angular.
 Custom validators are implemented as separate functions inside the
component.ts file.
 these functions can be added to the list of other validators configured for a
form control.
Program:
registration-form.component.ts:
import { Component, OnInit } from '@angular/core’;
---------------------------
export class RegistrationFormComponent implements
OnInit {
registerForm!: FormGroup;
submitted!:boolean;
constructor(private formBuilder: FormBuilder) { }
ngOnInit() {

Reactive Forms
this.registerForm = this.formBuilder.group({
firstName: ['', Validators.required],
lastName: ['', Validators.required],
address: this.formBuilder.group({
street: [],
zip: [],
city: []
}),
email: ['',[Validators.required,validateEmail]]
});}}
function validateEmail(c: FormControl): any {
let EMAIL_REGEXP = /^([a-zA-Z0-9_-.]+)@([a-zA-Z0-
9_-.]+).([a-zA-Z]{2,5})$/;
return EMAIL_REGEXP.test(c.value) ? null : {
emailInvalid: {
message: "Invalid Format!"
}};}

Reactive Forms
registration-form.component.html:
------------------------------------
<h1>Registration Form</h1>
<form [formGroup]="registerForm">
<h3> Employee Details </h3>
<p>First Name: {{
registerForm.get('firstName')?.value }} </p>
<p> Last Name: {{
registerForm.get('lastName')?.value }} </p>
-----------------------------------------
<p> Street: {{
registerForm.get('address.street')?.value }}</p>
<p> City: {{ registerForm.get('address.city')?.value
}}</p>
<p>Email: {{ registerForm.get('email')?.value
}}</p></div></div>

Reactive Forms
Output:

Template Driven forms
• While creating forms, there can be situations for validations for which built-in
validators are not available.
• Few such examples include validating a phone number, validating if the
password and confirm password fields matches or not, etc.
• In such situations, we can create custom validators to implement the required
functionality.
Program:
course.ts:
export class Course {
constructor(
public courseId: number,
public courseName: string,
public duration: string,
public email: string
) { }
}

course-form.component.ts:
import { Course } from './course’;
-------------------
export class CourseFormComponent {
course: Course = new Course(1, 'Angular 2', '4 days',
'devikan4353@gmail.com');
submitted = false;
onSubmit() { this.submitted = true; }
}
email.validator.ts:
import { Directive } from '@angular/core';
import { NG_VALIDATORS, FormControl, Validator } from
'@angular/forms';
@Directive({
selector: '[validateEmail]',
------------------------- })

export class EmailValidator implements Validator {
validate(control: FormControl): any {
const emailRegexp =
/^([a-zA-Z0-9_-.]+)@([a-zA-Z0-9_-.]+).([a-
zA-Z]{2,5})$/;
if (!emailRegexp.test(control.value)) {
return { emailInvalid: 'Email is invalid' };
}
return null;
}
}
app.module.ts:
----------------------------
import { EmailValidator } from './course-
form/email.validator';

@NgModule({
declarations: [
AppComponent,
CourseFormComponent,
EmailValidator
],
--------------------------
})
course-form.component.html:
<div [hidden]="submitted">
<h1>Course Form</h1>
<form (ngSubmit)="onSubmit()" #courseForm="ngForm">
<label for="id">Course Id</label>
-------------------------------

<label for="name">Course Name</label>
-------------------------------
<div [hidden]="duration.valid || duration.pristine"
class="alert alert-danger">Duration is required</div>
</div>
-------------------------------
<h2>You submitted the following:</h2>
--------------------------------
<div class="row">
<div class="col-xs-3">Email</div>
<div class="col-xs-9 pull-left">{{ course.email
}}</div></div>
<br><button class="btn btn-default"
(click)="submitted=false">Edit</button>
</div></div>

App.component.html:
<app-course-form></app-course-form>
Output:

Services Basics
• A service in Angular is a class that contains some functionality that can be
reused across the application. A service is a singleton object. Angular services
are a mechanism of abstracting shared code and functionality throughout the
application.
• Angular Services come as objects which are wired together using dependency
injection.
• Angular provides a few inbuilt services also can create custom services.
• Services can be used to:
1.share the code across components of an application.
2.make HTTP requests.
• Create a new component: ng generate component book
• Creating a Service
• To create a service class, use the following command:
• Command: ng generate service book

Services Basics
Program:
book.ts:
export class Book {
id!: number;
name!: string;}
books-data.ts:
import { Book } from './book';
export let BOOKS: Book[] = [{ id: 1, name: 'HTML 5' },
{ id: 2, name: 'CSS 3' },
{ id: 3, name: 'Java Script' },
{ id: 4, name: 'Ajax Programming' },
{ id: 5, name: 'jQuery' },
{ id: 6, name: 'Mastering Node.js' },
{ id: 7, name: 'Angular JS 1.x' },
{ id: 8, name: 'Core Java' },
{ id: 9, name: 'Backbone JS' },{ id: 10, name:
'MongoDB Basics’ } ];

Services Basics
book.service.ts:
import { Injectable } from '@angular/core';
import { BOOKS } from './book.data';
@Injectable({
providedIn: 'root'
})
export class BookService {
getBooks() {
return BOOKS; }}
book.component.ts:
import { BookService } from './book.service';
@Component({
selector: 'app-book',
templateUrl: './book.component.html',
styleUrls: ['./book.component.css’] })

Services Basics
export class BookComponent implements OnInit {
books!: Book[];
constructor(private bookService: BookService) { }
getBooks() {
this.books = this.bookService.getBooks();
}
ngOnInit() {
this.getBooks();
}
}
book.component.html:
<h2>My Books</h2>
<ul class="books">
<li *ngFor="let book of books">
<span class="badge">{{book.id}}</span>
{{book.name}}
</li></ul>

Services Basics
book.component.css:
.books {
margin: 0 0 2em 0;
list-style-type: none;
padding: 0;
width: 13em;
}
.books li {
cursor: pointer;
position: relative;
left: 0;
background-color:#eee;
margin: 0.5em;
padding: 0.3em 0;
height: 1.5em;
border-radius: 4px;
}

Services Basics
.books li:hover {
color: #607d8b;
background-color: #ddd;
left: 0.1em; }
.books .badge {
display: inline-block;
font-size: small;
color: white;
padding: 0.8em 0.7em 0 0.7em;
background-color: green;
line-height: 0.5em;
position: relative;
left: -1px;
top: -4px;
height: 1.8em;
margin-right: 0.8em;
border-radius: 4px 0 0 4px;
}

Services Basics
app.component.html:
<app-book></app-book>
Output:

RxJS Observables
RxJS
• Reactive Extensions for JavaScript (RxJS) is a third-party library used by
the Angular team.
• RxJS is a reactive streams library used to work with asynchronous streams of
data.
• Observables, in RxJS, are used to represent asynchronous streams of data.
Observables are a more advanced version of Promises in JavaScript
Program:
app.component.ts:
import { Observable } from 'rxjs';
@Component({
})

RxJS Observables
data!: Observable<number>;
myArray: number[] = [];
errors!: boolean;
finished!: boolean;
fetchData(): void {
this.data = new Observable(observer => {
setTimeout(() => { observer.next(43); }, 1000),
setTimeout(() => { observer.next(54); }, 2000),
setTimeout(() => { observer.complete(); }, 3000);
});
this.data.subscribe((value) =>
this.myArray.push(value),
error => this.errors = true,
() => this.finished = true);
}
}

RxJS Observables
app.component.html:
<b> Using Observables In Angular!</b>
<h6 style="margin-bottom: 0">VALUES:</h6>
<div *ngFor="let value of myArray">{{ value }}</div>
<div style="margin-bottom: 0">ERRORS: {{ errors
}}</div>
<div style="margin-bottom: 0">FINISHED: {{ finished
}}</div><button style="margin-top: 2rem"
(click)="fetchData()">Fetch Data</button>
Output:

Server Communication
using HttpClient
 Most front-end applications communicate with backend services using
HTTP Protocol
 While making calls to an external server, the users must continue to be
able to interact with the page. That is, the page should not freeze until the
HTTP request returns from the external server. So, all HTTP requests are
asynchronous.
 HttpClient from @angular/common/http to communicate must be used
with backend services.
 Additional benefits of HttpClient include testability features, typed request
and response objects, request and response interception, Observable APIs,
and streamlined error handling.
 HttpClientModule must be imported from @angular/common/http in the
module class to make HTTP service available to the entire module. Import
HttpClient service class into a component’s constructor. HTTP methods
like get, post, put, and delete are made used off.
 JSON is the default response type for HttpClient

using HttpClient
Program:
Backend Environment Creation:
Program:
app.js:
var express = require('express');
var router = require('./routes/index');
var cors = require('cors');
var app = express();
var bodyParser = require('body-parser');

using HttpClient
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: true }));
app.use(function (req, res, next) {
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Methods",
"GET,HEAD,OPTIONS,POST,PUT,DELETE");
res.header("Access-Control-Allow-Headers",
"Origin, X-Requested-With, Content-Type, Accept, x-
client-key, x-client-token, x-client-secret,
Authorization");
next();
});
app.use(cors())
app.options('*', cors())
app.use('/', router);
app.listen(3020, function () {
console.log('Server is up and running...’); });

using HttpClient
books.json:
[{
"id": 1,
"name": "HTML 5"
},{
"id": 2,
"name": "CSS 3"
},{
"id": 3,
"name": "Java Script"
},{
"id": 4,
"name": "Ajax Programming"
},{
"id": 5,
"name": "jQuery"
},

using HttpClient
{
"id": 6,
"name": "Mastering Node.js"
},{
"id": 7,
"name": "Angular JS 1.x"
},{
"id": 8,
"name": "ng-book 2"
},{
"id": 9,
"name": "Backbone JS"
},{
"id": 10,
"name": "Yeoman"
}
]

using HttpClient
index.js:
var express = require('express');
var bookList = [{ "id": 1, "name": "HTML 5" },
{ "id": 2, "name": "CSS 3" },
{ "id": 3, "name": "Java Script" },
{ "id": 4, "name": "Ajax Programming" },
{ "id": 5, "name": "jQuery" },
{ "id": 6, "name": "Mastering Node.js" },
{ "id": 7, "name": "Angular JS 1.x" },
{ "id": 8, "name": "ng-book 2" },
{ "id": 9, "name": "Backbone JS" },
{ "id": 10, "name": "Yeoman" }
]
var router = express.Router();
var path = require('path');
router.get('/', function (req, res, next) {
console.log("hi")
})

using HttpClient
router.post('/addBook', function (req, res) {
res.setHeader("Access-Control-Allow-Origin",
"*");
res.setHeader("Access-Control-Allow-
Credentials", "true");
res.setHeader("Access-Control-Allow-Methods",
"POST, GET, OPTIONS, DELETE");
res.setHeader("Access-Control-Allow-Headers",
"Content-Type, Accept, X-Requested-With, remember-
me");
var body = req.body;
bookList.push(body)
res.json(body);});
router.delete('/bookList/:id', function (req, res) {
var id = req.params.id
var index = bookList.findIndex(book => book.id ==
id)

using HttpClient
bookList.splice(index, 1);
res.json(bookList);
});
router.get('/bookList', function (req, res) {
"*");
"*");
res.json(bookList);
});
router.put('/update', function (req, res) {
var obj = bookList.findIndex(book => book.id ==
req.body.id)
bookList[obj] = req.body
res.json(bookList);
});
module.exports = router;

using HttpClient
FrontEnd Code:
book.component.css:
.books {
margin: 0 0 2em 0;
list-style-type: none;
padding: 0;
width: 13em;
}
.books li {
cursor: pointer;
position: relative;
left: 0;
background-color:#eee;
margin: 0.5em;
padding: 0.3em 0;
height: 1.5em;
border-radius: 4px;
}

using HttpClient
.books li:hover {
color: #607d8b;
background-color: #ddd;
left: 0.1em;
}
.books .badge {
font-size: small;
color: white;
padding: 0.8em 0.7em 0 0.7em;
background-color: green;
line-height: 0.5em;
position: relative;
left: -1px;
top: -4px;
height: 1.8em;
margin-right: 0.8em;
border-radius: 4px 0 0 4px;}

using HttpClient
<h2>{{ title }}</h2>
<h2>Books List</h2>
<ul class="books">
<span class="badge">{{ book.id }}</span> {{
book.name }}
</li>
</ul>
<button class="btn btn-primary" (click)="ADD_BOOK =
true">Add Book</button> 
-------------------------------------
<div *ngIf="ADD_BOOK">
<table>
<tr>
<td>Enter Id of the book:</td>
<td>
<input type="number" #id /></td></tr>

using HttpClient
---------------------
<button class="btn btn-primary"
(click)="addBook(id.value, name.value); ADD_BOOK =
false">
Add Record
</button>
</td>
</tr></table>
<br /></div>
<div *ngIf="UPDATE_BOOK">
<table>
<tr>
<td>Enter Id of the book:</td>
<td>
<input type="number" #id />
</td></tr><br />
----------------------------------

using HttpClient
<button class="btn btn-primary"
(click)="deleteBook(id.value); DELETE_BOOK = false">
Delete Record
</button>
</td>
</tr>
</table>
</div>
<div class="error" *ngIf="errorMessage">{{
errorMessage }}</div>
book.component.ts:
import { BookService } from './book.service';
import { Book } from './book’;
----------------------

using HttpClient
title = ' Server Communication using HttpClient ';
books!: Book[];
errorMessage!: string;
ADD_BOOK!: boolean;
UPDATE_BOOK!: boolean;
DELETE_BOOK!: boolean;
getBooks() {
this.bookService.getBooks().subscribe({
next: books => this.books = books,
error:error => this.errorMessage = <any>error
})
}
addBook(bookId: string, name: string): void {
let id=parseInt(bookId)

using HttpClient
this.bookService.addBook({id, name })
.subscribe({next:(book: any) =>
this.books.push(book)});
}
updateBook(bookId: string, name: string): void {
this.bookService.updateBook({ id, name })
.subscribe({next:(book: any) => this.books =
book});
}
deleteBook(bookId: string): void {
this.bookService.deleteBook(id)
.subscribe({next:(book: any) => this.books =
book});
}ngOnInit() {
this.getBooks();
}}

using HttpClient
book.service.ts:
import { HttpClient, HttpErrorResponse, HttpHeaders
} from '@angular/common/http’;
--------------------------------------
booksUrl = 'http://localhost:3020/bookList';
constructor(private http: HttpClient) { }
getBooks(): Observable<Book[]> {
return
---------------------------------------}
updateBook(book: Book): Observable<any> {
const options = new HttpHeaders({ 'Content-
Type': 'application/json' });
-------------------------------------
deleteBook(bookId: number): Observable<any> {
const url = `${this.booksUrl}/${bookId}`;

using HttpClient
return this.http.delete(url).pipe(
catchError(this.handleError));
}
private handleError(err: HttpErrorResponse):
Observable<any> {
let errMsg = '';
if (err.error instanceof Error) {
-----------------------------
console.log(`Backend returned code ${err.status}`);
errMsg = err.error.status;
}
return throwError(()=>errMsg);}}
book.ts:
export class Book {
id!: number;
name!: string;}

using HttpClient
books-data.ts:
export let BOOKS: Book[] = [
{ id: 1, name: 'HTML 5' },
{ id: 2, name: 'CSS 3' },
{ id: 3, name: 'Java Script' },
{ id: 4, name: 'Ajax Programming' },
{ id: 5, name: 'jQuery' },
{ id: 6, name: 'Mastering Node.js' },
{ id: 7, name: 'Angular JS 1.x' },
{ id: 8, name: 'Core Java' },
{ id: 9, name: 'Backbone JS' },
{ id: 10, name: 'MongoDB Basics' }
];

using HttpClient
app.module.ts:
import { BrowserModule } from '@angular/platform-
browser’;
-----------------------
@NgModule({
imports: [BrowserModule, HttpClientModule],
declarations: [AppComponent, BookComponent],
providers: [],
})
app.component.html:
<app-book></app-book>

using HttpClient
Output:

Communicating with different
backend services using Angular
HttpClient
• Angular can also be used to connect to different services written in
different technologies/languages. For example, we can make a call from
Angular to Node/Express or Java or Mainframe or .Net services, etc.
Program:
mobiles.json:
[{
"productId": 1,
"productName": "Samsung Galaxy Note 7",
"productCode": "MOB-120",
"description": "64GB, Coral Blue",
"price": 800,
"imageUrl":
"assets/imgs/samsung_note7_coralblue.jpg",
"manufacturer": "Samsung",
"ostype": "Android",
"rating": 4 },

HttpClient
{
"productId": 2,
"productName": "Samsung Galaxy Note 7",
"productCode": "MOB-124",
"description": "64GB, Gold",
"price": 850,
"imageUrl":
"assets/imgs/samsung_note7_gold.jpg",
"manufacturer": "Samsung",
"ostype": "Android",
"rating": 4
}
]

HttpClient
tablets.json :
[{
"productId": 1,
"productName": "Apple iPad Mini 2",
"productCode": "TAB-120",
"description": "16GB, White",
"price": 450,"imageUrl":
"assets/imgs/apple_ipad_mini.jpg",
"manufacturer": "Apple","ostype": "iOS",
"rating": 4 },
{ "productId": 2,
"productName": "Apple iPad Air2",
"productCode": "TAB-124",
"description": "64GB, Black","price": 600,
"imageUrl": "assets/imgs/ipad_air.jpg",
"manufacturer": "Apple","ostype": "iOS",
"rating": 3
}]

HttpClient
product.service.ts:
import { Injectable } from '@angular/core’;
-------------------------
export class ProductService {
selectedProducts: any = [];
products: any = [];
producttype="tablet";
username: string = '';
sessionStorage
constructor(private http: HttpClient) {
if(sessionStorage.getItem('selectedProducts'))
{this.selectedProducts =
JSON.parse(sessionStorage.getItem('selectedProducts')
+ '');
}
}

HttpClient
getProducts(): Observable<Product[]> {
if (this.producttype === 'tablet') {
return
this.http.get<Product[]>('./assets/products/tablets.js
on').pipe(
tap((products) => this.products =
products),
}
--------------------------------------
private handleError(err: HttpErrorResponse) {
return throwError(() => err.error() || 'Server
error');
}
}

HttpClient
products.module.ts:
import { ProductsRoutingModule } from './products-
routing.module';
import { ProductListComponent } from './product-
list/product-list.component’;
--------------------
import { RatingComponent } from './rating.component';
import { ProductService } from './product.service';
import { AuthGuardService } from './auth-guard.service';
@NgModule({
imports: [
CommonModule,
FormsModule,
ProductsRoutingModule ],
--------------------------------------
export class ProductsModule { }

HttpClient
product-list.component.ts:
import { ProductService } from '../product.service';
import { Cart } from '../cart/Cart';
import { Product } from '../product’;
----------------------------------------
export class ProductListComponent implements OnInit,
AfterViewInit {
chkman: any = [];
chkmanos: any = [];
rate: number = 0;
pageTitle = 'mCart’;imageWidth = 80;
imageHeight = 120;imageMargin = 12;
showImage = false;
listFilter: string = '';
manufacturers = [{ 'id': 'Samsung', 'checked': false
},

HttpClient
{ 'id': 'Microsoft', 'checked': false },
{ 'id': 'Apple', 'checked': false },
{ 'id': 'Micromax', 'checked': false }
];
os = [{ 'id': 'Android', 'checked': false },
{ 'id': 'Windows', 'checked': false },
{ 'id': 'iOS', 'checked': false }];
price_range = [{ 'id': '300-450', 'checked': false
},
-------------------------------------------
tabselect(producttype: string) {
this.manufacturers = [{ 'id': 'Samsung',
'checked': false },
{ 'id': 'Microsoft', 'checked': false },
{ 'id': 'Apple', 'checked': false },
{ 'id': 'Micromax', 'checked': false } ];

HttpClient
this.os = [{ 'id': 'Android', 'checked': false },
{ 'id': 'Windows', 'checked': false },
{ 'id': 'iOS', 'checked': false }];
this.price_range = [{ 'id': '300-450',
'checked': false },
{ 'id': '450-600', 'checked': false },
{ 'id': '600-800', 'checked': false },
{ 'id': '800-1000', 'checked': false }];
---------------------------
error: error => this.errorMessage = error
});
}
onChange(value: string) {
this.sortoption = value;
}
}

HttpClient
Output:

Routing Basics, Router Links
• Routing means navigation between multiple views on a single page.
• Routing allows to express some aspects of the application's state in the URL. The
full application can be built without changing the URL.
• Routing allows to:
❖ Navigate between the views
❖ Create modular applications
• ng generate component dashboard
• ng generate component bookDetail
• ng g c PageNotFound
• Run Backend code parallel
• And also install service book and book.ts and books-data in book component
Program:
dashboard.component.ts:
import { Router } from '@angular/router’;
------------------------------------------------------------
@Component({
templateUrl: './dashboard.component.html',
styleUrls: ['./dashboard.component.css']})

export class DashboardComponent implements OnInit {
books: Book[] = [];
constructor(
private router: Router,
private bookService: BookService) { }
ngOnInit(): void {
this.bookService.getBooks()
.subscribe({next:books => this.books =
books.slice(1, 5)});
}
gotoDetail(book: Book): void {
this.router.navigate(['/detail', book.id]);
}
}

dashboard.component.html:
<h3>Top Books</h3>
<div class="grid grid-pad">
<div *ngFor="let book of books"
(click)="gotoDetail(book)" class="col-1-4">
<div class="module book">
<h4>{{ book.name }}</h4>
</div>
</div>
</div>
dashboard.component.css:
class*="col-"] {
float: left;
}
*,
*:after,

book.service.ts:
import { HttpClient, HttpErrorResponse, HttpHeaders,
HttpResponse } from '@angular/common/http';
import { Observable, throwError } from 'rxjs’;
--------------------------------
booksUrl = 'http://localhost:3020/bookList';
private txtUrl = './assets/sample.txt';
constructor(private http: HttpClient) { }
getBooks(): Observable<Book[]> {
return this.http.get<any>(this.booksUrl,
{observe:'response'}).pipe(
tap((data: any) => console.log('Data Fetched:' +
JSON.stringify(data))),
map((data: any) => data.body),
}

---------------------------
console.log(`Backend returned code ${err.status}`);
errMsg = err.error.status;
}
return throwError(()=>errMsg); }}
book-detail.component.ts:
import { ActivatedRoute } from '@angular/router’;
-------------------------------
export class BookDetailComponent implements OnInit {
book!: Book;
error!: any;
constructor(
private bookService: BookService,
private route: ActivatedRoute
) { }

ngOnInit() {
this.route.paramMap.subscribe(params => {
this.bookService.getBook(params.get('id')).subscribe((
book) => {
this.book = book ?? this.book;
}); }); }
goBack() {
window.history.back();
}}
book-detail.component.html:
<div *ngIf="book">
<h2>{{ book.name }} details!</h2>
<div><label>Id: </label>{{ book.id }}</div>
<div><label>Name: </label> <input
[(ngModel)]="book.name" placeholder="name" />
</div><button (click)="goBack()">Back</button>
</div>

book-detail.component.css:
label {
width: 3em;
margin: 0.5em 0;
color: orange;
font-weight: bold;
}input {
height: 2em;
font-size: 1em;
padding-left: 0.4em;
}button {
margin-top: 20px;
font-family: Arial;
border: none;padding: 5px 10px;
border-radius: 4px;cursor: pointer;
cursor: hand;}

button:hover {
background-color: #cfd8dc;
}
button:disabled {
color: #ccc;
cursor: auto;
}
h2{
color:Orange;
}
page-not-found.component.html:
<div>
<h1>404 Error</h1>
<h1>Page Not Found</h1>
</div>

app-routing.module.ts:
import { RouterModule, Routes } from
'@angular/router';
import { BookComponent } from './book/book.component’;
-------------------------
const appRoutes: Routes = [
{ path: 'dashboard', component: DashboardComponent},
{ path: '', redirectTo: '/dashboard', pathMatch:
'full' },
{ path: 'books', component: BookComponent },
{ path: 'detail/:id', component: BookDetailComponent
},
{ path: '**', component: PageNotFoundComponent },
];
---------------------------------------------------
})
export class AppRoutingModule { }

app.module.ts :
import { BookComponent } from './book/book.component';
import { DashboardComponent } from
'./dashboard/dashboard.component';
import { BookDetailComponent } from './book-detail/book-
detail.component';
import { AppRoutingModule } from './app-routing.module';
import { PageNotFoundComponent } from './page-not-
found/page-not-found.component’;
-------------------------------------------
@NgModule({
imports: [BrowserModule, HttpClientModule, FormsModule,
AppRoutingModule],
declarations: [AppComponent, BookComponent,
DashboardComponent, BookDetailComponent,PageNotFound
PageNotFoundComponent ],
providers: [],bootstrap: [AppComponent]

app.component.ts:
@Component({
})
title = 'Tour of Books';}
app.component.html:
<h1>{{title}}</h1>
<nav>
<a [routerLink]='["/dashboard"]'
routerLinkActive="active">Dashboard</a>
<a [routerLink]='["/books"]'
routerLinkActive="active">Books</a>
</nav>
<router-outlet></router-outlet>

app.component.css:
h1 {
color: green;
font-size: 250%;
}h2, h3 {
color: #444;
font-weight: lighter;
}body {
margin: 2em;
}body, input[text], button {
color: #888;
font-family: Cambria, Georgia;
}a {
cursor: pointer;
cursor: hand;
}

button {
font-family: Arial;
background-color: #eee;border: none;
padding: 5px 10px;
border-radius: 4px;cursor: pointer;cursor: hand;
}button:hover {
background-color: #cfd8dc;
}button:disabled {
color: #aaa;
cursor: auto;
}nav a {
padding: 5px 10px;text-decoration: none;
margin-right: 10px;margin-top: 10px;
background-color: #eee;border-radius: 4px;
}

nav a:visited, a:link {
color: #607D8B;
}
nav a:hover {
color: #039be5;
background-color: #CFD8DC;
}
nav a.active {
color: green;
}
* {
}
styles.css :
body{
padding:10px;
}

book.component.ts:
import { BookService } from './book.service’;
------------------------
books!: Book[];
getBooks() {
next: books => this.books = books,
})
} ngOnInit(): void {
this.getBooks();
}
}

<h2>My Books</h2>
<ul class="books">
<span class="badge">{{ book.id }}</span>
{{book.name }}</li>
</ul><div class="error" *ngIf="errorMessage">{{
errorMessage }}</div>
Output:

Route Guards
• Angular route guards are interfaces provided by Angular which, when
implemented, allow us to control the accessibility of a route based on
conditions provided in class implementation of that interface.
• Here are some types of Angular guards: CanActivate, CanActivateChild,
CanLoad, CanDeactivate and Resolve.
• Using canActivate, access can be permitted to only authenticated users.
• Syntax:
Class GuardService implements CanActivate{
canActivate( ): boolean {
}
}
Program:
login.component.html:
<h3 style="position: relative; left: 60px;
color:green">Login Form</h3>
<div *ngIf="invalidCredentialMsg" style="color: red">
{{ invalidCredentialMsg }}
</div>

Route Guards
<br />
<div style="position: relative; left: 20px">
<form [formGroup]="loginForm"
(ngSubmit)="onFormSubmit()">
<p>User Name <input formControlName="username"
/></p>
<p>
Password
<input
type="password"
formControlName="password"
style="position: relative; left: 10px"
/>
</p>
<p><button class="btn-success"
type="submit">Submit</button></p>
</form>
</div>

Route Guards
login.component.ts:
import { FormBuilder, FormGroup } from
'@angular/forms';
import { Router } from '@angular/router';
import { LoginService } from './login.service';
@Component({
templateUrl: './login.component.html',
styleUrls: ['./login.component.css'],
})
export class LoginComponent {
invalidCredentialMsg!: string;
loginForm!: FormGroup;
constructor(
private loginService: LoginService,
private formbuilder: FormBuilder
)

Route Guards
{
this.loginForm = this.formbuilder.group({
username: [],
password: [],
});}
onFormSubmit(): void {
const uname = this.loginForm.value.username;
const pwd = this.loginForm.value.password;
this.loginService.isUserAuthenticated(uname, pwd)
.subscribe({next:(authenticated) => {
if (authenticated) {
this.router.navigate(['/books']);
} else {
this.invalidCredentialMsg = 'Invalid
Credentials. Try again.';
}
}});
}}

Route Guards
user.ts:
export class User {
constructor(public userId: number, public
username: string, public password: string) { }
}
login.service.ts:
import { Observable, of } from 'rxjs';
import { map } from 'rxjs/operators';
import { User } from './user';
const USERS = [
new User(1, 'user1', 'pass1'),
new User(2, 'user2', 'pass2')
];
const usersObservable = of(USERS);
@Injectable({
providedIn: 'root'
})

Route Guards
export class LoginService {
private isloggedIn = false;
getAllUsers(): Observable<User[]> {
return usersObservable; }
isUserAuthenticated(username: string, password:
string): Observable<boolean> {
return this.getAllUsers().pipe(
map(users => {const Authenticateduser =
users.find(user => (user.username === username) &&
(user.password === password));
if (Authenticateduser) {this.isloggedIn = true;
} else {
this.isloggedIn = false;
}return this.isloggedIn;
}) ); }
isUserLoggedIn(): boolean {
return this.isloggedIn;
} }

Route Guards
login-guard.service.ts:
import { CanActivate, Router } from '@angular/router';
import { LoginService } from './login.service';
@Injectable({
providedIn: 'root'
})
export class LoginGuardService implements CanActivate
{
constructor(private loginService: LoginService,
private router: Router) { }
canActivate(): boolean {
if (this.loginService.isUserLoggedIn()) {
return true;
}
this.router.navigate(['/login']);
return false;
}}

Route Guards
app.module.ts:
--------------------------
import { AppRoutingModule } from './app-
routing.module';
found/page-not-found.component';
import { LoginComponent } from
'./login/login.component';
@NgModule({
imports: [BrowserModule, HttpClientModule,
ReactiveFormsModule,FormsModule, AppRoutingModule],
declarations: [AppComponent, LoginComponent,
BookComponent, DashboardComponent,
BookDetailComponent, PageNotFoundComponent],
providers: [],

Route Guards
import { RouterModule, Routes } from '@angular/router’;
----------------------------------------
import { LoginGuardService } from './login/login-
guard.service';
import { LoginComponent } from './login/login.component';
{ path: 'dashboard', component: DashboardComponent },
{ path: '', redirectTo: '/dashboard', pathMatch: 'full'},
{ path: 'books', component: BookComponent ,
canActivate:[LoginGuardService] },
{ path: 'detail/:id', component: BookDetailComponent},
{path: 'login',component:LoginComponent},
{ path: '**', component: PageNotFoundComponent },
];

Route Guards
@NgModule({
imports: [
RouterModule.forRoot(appRoutes)
],exports: [
RouterModule
]
})
Output:

Asynchronous Routing
• Asynchronous routing is the most straightforward method of routing signals.
Any asynchronous route can be defined in terms of two signals: a source and
a destination.
• When an Angular application has a lot of components, it will increase the size
of the application. In such cases, the application takes a lot of time to load.
• To overcome this problem, asynchronous routing is preferred, i.e, modules
must be loaded lazily only when they are required instead of loading them at
the beginning of the execution
Lazy Loading has the following benefits:
❖ Modules are loaded only when the user requests for it
❖ Load time can be speeded up for users who will be visiting only certain
areas of the application.
Lazy Loading Route Configuration:
• To apply lazy loading on modules, create a separate routing configuration file
for that module and map an empty path to the component of that module.

book-routing.module.ts:
import { RouterModule, Routes } from
'@angular/router';
import { BookComponent } from './book.component';
import { LoginGuardService } from '../login/login-
guard.service';
const bookRoutes: Routes = [
{
path: '',
component: BookComponent,
canActivate: [LoginGuardService]
}
];@NgModule({
imports: [RouterModule.forChild(bookRoutes)],
exports: [RouterModule]
})
export class BookRoutingModule { }

book.module.ts:
import { CommonModule } from '@angular/common';
import { BookRoutingModule } from './book-
routing.module';
@NgModule({
imports: [CommonModule, BookRoutingModule],
declarations: [BookComponent]
})
export class BookModule { }
import { RouterModule, Routes } from'@angular/router';
import { BookDetailComponent } from './book-
detail/book-detail.component';
import { BookComponent } from './book/book.component';

import { DashboardComponent } from
'./dashboard/dashboard.component';
import { LoginGuardService } from './login/login-
guard.service';
import { LoginComponent } from'./login/login.component';
{ path: '', redirectTo: '/login', pathMatch: 'full' },
{ path: 'login', component: LoginComponent },
{ path: 'books', loadChildren: () =>
import('./book/book.module').then(m => m.BookModule) },
{ path: 'detail/:id', component: BookDetailComponent} ,
{ path: '**', component: PageNotFoundComponent }
];
---------------------------------------------
})export class AppRoutingModule { }

app.module.ts:
----------------------------------
import { BookDetailComponent } from './book-detail/book-
detail.component';
@NgModule({
ReactiveFormsModule,FormsModule, AppRoutingModule],
declarations: [AppComponent, LoginComponent,
DashboardComponent, BookDetailComponent,
PageNotFoundComponent],
providers: [],

Nested Routes
• In Angular, you can also create sub-routes or child routes for your components
which means in an application there will be one root route just like a root
component/root module and other routes will be configured for their respective
components. Configuring routes module-wise is the best practice to make
modular Angular applications.
Syntax:
import { RouterModule, Routes } from '@angular/router';
import { ParentComponent } from './parent.component';
import { ChildComponent } from './child.component';
const routes: Routes = [
{
path: 'parent',
component: ParentComponent,
children: [
{
path: 'child',
component: ChildComponent

Nested Routes
} ]
}
];
@NgModule({
imports: [RouterModule.forChild(routes)],
exports: [RouterModule]
})export class ParentRoutingModule { }
Program:
app.module.ts:
-----------------
@NgModule({
ReactiveFormsModule, AppRoutingModule],
------------------------------

Nested Routes
{ path: '', redirectTo: '/login', pathMatch: 'full' },
{ path: 'login', component: LoginComponent },
{ path: 'books', loadChildren: () =>
import('./book/book.module').then(m => m.BookModule) },
{ path: '**', component: PageNotFoundComponent }
];
-----------------------------------------
})

Nested Routes
app.component.html:
<h1>{{title}}</h1>
<nav>
<a [routerLink]='["/books"]'
routerLinkActive="active">Books</a>
<a [routerLink]='["/books/dashboard"]'
routerLinkActive="active">Dashboard</a>
</nav><router-outlet></router-outlet>
book.module.ts:
import { BookComponent } from './book.component’;
import { BookRoutingModule } from './bookrouting.module';
import { CommonModule } from '@angular/common';
@NgModule({
imports: [ CommonModule, BookRoutingModule,
FormsModule],
----------------------------------------------
})export class BookModule { }

Nested Routes
book-routing.module.ts:
import { BookDetailComponent } from '../book-detail/book-
detail.component’;
-----------------------------------
const bookRoutes: Routes = [
{
path: '',
component: BookComponent,
children: [
{ path: 'detail/:id', component: BookDetailComponent }
],
canActivate: [LoginGuardService]
}];
-------------------------------------
})export class BookRoutingModule { }

Nested Routes
<br/>
<h2>MyBooks</h2>
<ul class="books">
<li *ngFor="let book of books "
(click)="gotoDetail(book)">
<span class="badge">{{book.id}}</span>
{{book.name}}
</li>
</ul>
<div>
<router-outlet></router-outlet>
</div>
<div class="error"
*ngIf="errorMessage">{{errorMessage}}</div>

Nested Routes
book.component.ts:
import { BookService } from './book.service’;
-------------------------
books: Book[]=[];
constructor(private bookService: BookService, private
router: Router) { }
getBooks() {
next: books => {console.log(books);this.books =
books},
})
}

Nested Routes
gotoDetail(book: Book): void {
this.router.navigate(['/books/detail/', book.id]);
}
ngOnInit(): void {
this.getBooks();
}
}
book-detail.component.html:
<div *ngIf="book">
<h2>{{ book.name }} details!</h2>
<div><label>Id: </label>{{ book.id }}</div>
<div>
<label>Name: </label> <input [(ngModel)]="book.name"
placeholder="name" />
</div>
<button (click)="goBack()">Back</button>
</div>

Nested Routes
book-detail.component.ts:
import { ActivatedRoute } from '@angular/router';
import { Book } from '../book/book';
import { BookService } from '../book/book.service’;
---------------------------
export class BookDetailComponent implements OnInit {
book!: Book;
error!: any;
constructor(
private bookService: BookService,
private route: ActivatedRoute
) { }
ngOnInit() {
this.route.paramMap.subscribe(params => {
this.bookService.getBook(params.get('id')).subscribe((boo
k) => {
this.book = book ?? this.book;});

Nested Routes
});
}
goBack() {
window.history.back();
}
}
dashboard.component.html:
<h3>Top Books</h3>
<div class="grid grid-pad">
<div *ngFor="let book of books"
(click)="gotoDetail(book)" class="col-1-4">
<div class="module book">
<h4>{{ book.name }}</h4>
</div>
</div>
</div>

Nested Routes
dashboard.component.ts:
import { Book } from '../book/book';
import { BookService } from '../book/book.service’;
-----------------------------
export class DashboardComponent implements OnInit {
books: Book[] = [];
constructor(
private bookService: BookService) { }
ngOnInit(): void {
this.bookService.getBooks()
.subscribe(books => this.books =
books.slice(1, 5));
}gotoDetail(book: Book): void {
this.router.navigate(['/books/detail', book.id]);
}}

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