Riley Lambert

Riley Lambert

1560831365

MVC in an Angular World

When designing software with a user interface, it is important to structure the code in a way that makes it easy to extend and maintain. Over time, there have been a few approaches in separating out responsibilities of the different components of an application. Although there is plenty of literature on these design patterns around, it can be very confusing for a beginner to understand the features of limitations of the different patterns and the differences between them.


Table of Contents

In this tutorial, I want to talk about the major two approaches, the Model-View-Controller (MVC) pattern and the Model-View-ViewModel (MVVM) pattern. In the MVVM pattern, the controller is replaced by a ViewModel. The main differences between these two components are the direction of dependency between the View on one side, and the Controller or ViewModel on the other side.

I will be developing the ideas and explaining the patterns by example using a browser application written in TypeScript and Angular. TypeScript is an extension of JavaScript that adds type information to the code. The application will mimic the popular Notes application on MacOS/iOS. Angular enforces the MVVM pattern. Let’s dive in and see the main differences between the MVC and the MVVM patterns.


Set Up Your Application with Angular CLI

To start off you will need to install Angular CLI. Make sure you have Node and npm installed first. If you haven’t done so, visit node.js.org and follow the instructions to download and install Node. Then, open a terminal on your computer and run the npm command to install Angular CLI.

npm install -g @angular/cli@7.2.1

Depending on your system configuration, you may have to run this command as the system administrator using sudo. This will install the ng command globally on your system. ng is used to create, manipulate, test, and build Angular applications. You can create a new Angular application by running ng new in a directory of your choice.

ng new AngularNotes

This will start a wizard that takes you through a couple of questions about the new application and then creates the directory layout and some files with skeleton code. The first question regards the inclusion of the routing module. Routing lets you navigate to different components in the application by changing the browser path. You will need to answer yes to this question. The second question lets you choose the CSS technology which you want to use. Because I will only include some very simple style sheets, the plain CSS format will be sufficient. When you have answered the questions, the wizard will start downloading and installing all the necessary components.

You can use Material Design and its components to make the application look nice. These can be installed by using the npm command inside the application directory. The ng new command should have created a directory called AngularNotes. Navigate into that and run the following command.

npm install --save @angular/material@7.2.1 @angular/cdk@7.2.1 @angular/animations@7.2.0 @angular/flex-layout@7.0.0-beta.23

The src directory contains the application source code. Here, src/index.html is the main entry point for the browser. Open this file in a text editor of your choice and paste the following line into the <head> section. This will load the font needed for the Material Icons.

<link href="https://fonts.googleapis.com/icon?family=Material+Icons" rel="stylesheet">

The src/style.css style sheet contains global styles. Open this file and paste the following styles into it.

@import "~@angular/material/prebuilt-themes/deeppurple-amber.css";

body {
margin: 0;
font-family: sans-serif;
}

h1, h2 {
text-align: center;
}

Next, open src/app/app.module.ts. This file contains the imports for all the modules that you want to be globally available. Replace to contents of this file with the following code.

import { BrowserModule } from ‘@angular/platform-browser’;
import { NgModule } from ‘@angular/core’;
import { FormsModule, ReactiveFormsModule } from ‘@angular/forms’;
import { BrowserAnimationsModule } from ‘@angular/platform-browser/animations’;
import { FlexLayoutModule } from “@angular/flex-layout”;

import { MatToolbarModule,
MatMenuModule,
MatIconModule,
MatInputModule,
MatFormFieldModule,
MatButtonModule,
MatListModule,
MatDividerModule } from ‘@angular/material’;

import { AppRoutingModule } from ‘./app-routing.module’;
import { AppComponent } from ‘./app.component’;

@NgModule({
declarations: [
AppComponent,
],
imports: [
BrowserModule,
BrowserAnimationsModule,
FlexLayoutModule,
FormsModule,
ReactiveFormsModule,
MatToolbarModule,
MatMenuModule,
MatIconModule,
MatInputModule,
MatFormFieldModule,
MatButtonModule,
MatListModule,
MatDividerModule,
AppRoutingModule,
],
bootstrap: [AppComponent]
})
export class AppModule { }

At this point, I could start showing you how to create the application layout in the file src/app/app.component.html. But this would already have me dive into the discussion of the application architecture. Instead, in the next section, I want to first guide you through the implementation of the Model. I will be discussing the View and its relation to the ViewModel in the following section.


The Model

The model contains the business end of your application. For simple CRUD (Create Read Update Delete) applications, the model is usually a simple data model. For more complex applications, the model will naturally reflect that increase in complexity. In the application you see here, the model will hold a simple array of text notes. Each note has an ID, a title, and a text. In Angular, the model is coded up in so-called services. The ng command lets you create a new service.

ng generate service Notes

This will create two new files, src/app/notes.service.ts and src/app/notes.service.spec.ts. You can ignore the second of these files in this tutorial, just as the other .spec.ts files. These files are used for unit testing the code. In an application that you want to release for production, you would write your tests there. Open src/app/notes.service.ts and replace its contents with the following code.

import { Injectable } from ‘@angular/core’;
import { BehaviorSubject, Observer } from ‘rxjs’;

export class NoteInfo {
id: number;
title: string;
}

export class Note {
id: number;
title: string;
text: string;
}

@Injectable({
providedIn: ‘root’
})
export class NotesService {
private notes: Note[];
private nextId = 0;
private notesSubject = new BehaviorSubject<NoteInfo[]>([]);

constructor() {
this.notes = JSON.parse(localStorage.getItem(‘notes’)) || [];
for (const note of this.notes) {
if (note.id >= this.nextId) this.nextId = note.id+1;
}
this.update();
}

subscribe(observer: Observer<NoteInfo[]>) {
this.notesSubject.subscribe(observer);
}

addNote(title: string, text: string): Note {
const note = {id: this.nextId++, title, text};
this.notes.push(note);
this.update();
return note;
}

getNote(id: number): Note {
const index = this.findIndex(id);
return this.notes++[++index];
}

updateNote(id: number, title: string, text: string) {
const index = this.findIndex(id);
this.notes++[++index] = {id, title, text};
this.update();
}

deleteNote(id: number) {
const index = this.findIndex(id);
this.notes.splice(index, 1);
this.update();
}

private update() {
localStorage.setItem(‘notes’, JSON.stringify(this.notes));
this.notesSubject.next(this.notes.map(
note => ({id: note.id, title: note.title})
));
}

private findIndex(id: number): number {
for (let i=0; i<this.notes.length; i++) {
if (this.notes[i].id === id) return i;
}
throw new Error(Note with id ${id} was not found!);
}
}

Near the top of the file you can see two class definitions, NoteInfo and Note. The Note class contains the full information on a note, while NoteInfo only contains the id and the title. The idea is that NoteInfo is much lighter and can be used in a list, displaying all note titles. Both Note and NoteInfo are simple data classes, containing no business logic. The logic is contained in NotesService, which acts as the Model of the application. It contains a number of properties. The notes property is an array of Notes objects. This array acts as the source of truth for the model. The functions addNote, getNote, updateNote, and deleteNote define the CRUD operations on the model. They all directly act on the notes array, creating, reading, updating, and deleting elements in the array. The nextId property is used as a unique ID by which a note can be referenced.

You will notice that, whenever the notes array is modified, the private update method is called. This method does two things. First, it saves the notes in the local storage. As long as the browser’s local storage has not been deleted, this will persist the data locally. This allows users to close the application and open it later on and still have access to their notes. In a real-world application, the CRUD operations would access a REST API on a different server, instead of saving the data locally.

The second action performed by update is to emit a new value on the notesSubject property. notesSubject is a BehaviorSubject from RxJS which contains an array of the condensed NoteInfo objects. The BehaviorSubject act as an observable to which any observer can subscribe. This subscription is made possible through the subscribe method of NotesService. Any observer that has subscribed will be notified whenever update is called.

The main thing to take away from the implementation of the Model is, that the Model is a standalone service that has no knowledge of any View or Controller. This is important in both, the MVC and the MVVM architecture. The Model must not have any dependency on the other components.


The View

Next, I’d like to turn your attention to the View. In Angular applications, the View lives inside the .html templates and the .css style sheets. I have already mentioned one of these templates in the file src/app/app.component.html. Open the file and paste the following content into it.

<mat-toolbar color=“primary” class=“expanded-toolbar”>
<span>
<button mat-button routerLink=“/”>{{title}}</button>
<button mat-button routerLink=“/”><mat-icon>home</mat-icon></button>
</span>
<button mat-button routerLink=“/notes”><mat-icon>note</mat-icon></button>
</mat-toolbar>
<router-outlet></router-outlet>

Why not add a bit of styling too? Open src/app/app.component.css and add the following style.

.expanded-toolbar {
justify-content: space-between;
align-items: center;
}

The app.component contains the main page layout, but not any meaningful content. You will have to add some components that will render any content. Use the ng generate command again like this.

ng generate component Home
ng generate component Notes

This generates two components. Each component is made up of a .html, .css, and a .ts file. For now, don’t worry about the .ts file. I’ll get to that in the next section. (Remember, there is also a .spec.ts file that I am ignoring completely in this tutorial.)

Open src/app/home/home.component.html and change the content to the following.

<h1>Angular Notes</h1>
<h2>A simple app showcasing the MVVM pattern.</h2>

Next, open src/app/notes/notes.component.html and replace the content with the code below.

<div fxLayout=“row” fxLayout.xs=“column” fxLayoutAlign=“center” class=“notes”>
<mat-list fxFlex=“100%” fxFlex.gt-sm=“20%”>
<mat-list-item _ngFor=‘let note of notes’>
<a>
{{note.title}}
</a>
</mat-list-item>
</mat-list>
<mat-divider fxShow=“false” fxShow.gt-sm _[_vertical]=“true”></mat-divider>
<mat-divider fxShow=“true” fxShow.gt-sm=“false” _[_vertical]=“false”></mat-divider>
<div fxFlex=“100%” fxFlex.gt-sm=“70%” _ngIf=“!editNote” class=“note-container”>
<h3>{{currentNote.title}}</h3>
<p>
{{currentNote.text}}
</p>
<div fxLayout=“row” fxLayoutAlign=“space-between center” >
<button mat-raised-button color=“primary”>Edit</button>
<button mat-raised-button color=“warn”>Delete</button>
<button mat-raised-button color=“primary”>New Note</button>
</div>
</div>
<div fxFlex=“100%” fxFlex.gt-sm=“70%” *ngIf=“editNote” class=“form-container”>
<form [formGroup]=“editNoteForm”>
<mat-form-field class=“full-width”>
<input matInput placeholder=“Title” formControlName=“title”>
</mat-form-field>

  &lt;mat-form-field class="full-width"&gt;
    &lt;textarea matInput placeholder="Note text" formControlName="text"&gt;&lt;/textarea&gt;
  &lt;/mat-form-field&gt;
  &lt;button mat-raised-button color="primary"&gt;Update&lt;/button&gt;
&lt;/form&gt;

</div>
</div>

The accompanying src/app/notes/notes.component.css should look like this.

.notes {
padding: 1rem;
}

.notes a {
cursor: pointer;
}

.form-container, .note-container {
padding-left: 2rem;
padding-right: 2rem;
}

.full-width {
width: 80%;
display: block;
}

So far, so good!

Have a look at src/app/notes/notes.component.html which represents the main View of the application. You will notice placeholders such as {{note.title}} which look like they can be filled with values. In the version shown above, the View does not seem to refer to any piece of code in the application.

If you were to follow the MVC pattern, the View would define slots into which the data could be inserted. It would also provide methods for registering a callback whenever a button is clicked. In this respect, the View would remain completely ignorant of the Controller. The Controller would actively fill the values and register callback methods with the View. Only the Controller would know about both the View and the Model and link the two together.

As you will see below, Angular takes a different approach, called the MVVM pattern. Here the Controller is replaced by a ViewModel. This will be the topic of the next section.


The ViewModel

The ViewModel lives in the .ts files of the components. Open src/app/notes/notes.component.ts and fill it with the code below.

import { Component, OnInit } from ‘@angular/core’;
import { Note, NoteInfo, NotesService } from ‘…/notes.service’;
import { BehaviorSubject } from ‘rxjs’;
import { FormGroup, FormBuilder, Validators } from ‘@angular/forms’;

@Component({
selector: ‘app-notes’,
templateUrl: ‘./notes.component.html’,
styleUrls: [‘./notes.component.css’]
})
export class NotesComponent implements OnInit {
notes = new BehaviorSubject<NoteInfo[]>([]);
currentNote: Note = {id:-1, title: ‘’, text:‘’};
createNote = false;
editNote = false;
editNoteForm: FormGroup;

constructor(private formBuilder: FormBuilder,
private notesModel: NotesService) { }

ngOnInit() {
this.notesModel.subscribe(this.notes);
this.editNoteForm = this.formBuilder.group({
title: [‘’, Validators.required],
text: [‘’, Validators.required]
});
}

onSelectNote(id: number) {
this.currentNote = this.notesModel.getNote(id);
}

noteSelected(): boolean {
return this.currentNote.id >= 0;
}

onNewNote() {
this.editNoteForm.reset();
this.createNote = true;
this.editNote = true;
}

onEditNote() {
if (this.currentNote.id < 0) return;
this.editNoteForm.get(‘title’).setValue(this.currentNote.title);
this.editNoteForm.get(‘text’).setValue(this.currentNote.text);
this.createNote = false;
this.editNote = true;
}

onDeleteNote() {
if (this.currentNote.id < 0) return;
this.notesModel.deleteNote(this.currentNote.id);
this.currentNote = {id:-1, title: ‘’, text:‘’};
this.editNote = false;
}

updateNote() {
if (!this.editNoteForm.valid) return;
const title = this.editNoteForm.get(‘title’).value;
const text = this.editNoteForm.get(‘text’).value;
if (this.createNote) {
this.currentNote = this.notesModel.addNote(title, text);
} else {
const id = this.currentNote.id;
this.notesModel.updateNote(id, title, text);
this.currentNote = {id, title, text};
}
this.editNote = false;
}
}

In the @Component decorator of the class, you can see the reference to the View .html and .css files. In the rest of the class, on the other hand, there is no reference to the View whatsoever. Instead, the ViewModel, contained in the NotesComponent class, exposes properties and methods that can be accessed by the View. This means that, compared to the MVC architecture, the dependency is reversed. The ViewModel has no knowledge of the View but provides a Model-like API that can be used by the View. If you take another look at src/app/notes/notes.component.html you can see that the template interpolation, such as {{currentNote.text}} directly accesses the properties of the NotesComponent.

The last step to make your application work is to tell the router which components are responsible for the different routes. Open src/app/app-routing.module.ts and edit the content to match the code below.

import { NgModule } from ‘@angular/core’;
import { Routes, RouterModule } from ‘@angular/router’;
import { HomeComponent } from ‘./home/home.component’;
import { NotesComponent } from ‘./notes/notes.component’;

const routes: Routes = [
{ path: ‘’, component: HomeComponent },
{ path: ‘notes’, component: NotesComponent },
];

@NgModule({
imports: [RouterModule.forRoot(routes)],
exports: [RouterModule]
})
export class AppRoutingModule { }

This will link the HomeComponent to the default route and the NotesComponent to the notes route.

For the main application component, I will define a few methods which will be implemented later on. Open src/app/app.component.ts and update the content to look like the following.

import { Component } from ‘@angular/core’;

@Component({
selector: ‘app-root’,
templateUrl: ‘./app.component.html’,
styleUrls: [‘./app.component.css’]
})
export class AppComponent {
public title = ‘Angular Notes’;
public isAuthenticated: boolean;

ngOnInit() {
this.isAuthenticated = false;
}

login() {
}

logout() {
}
}

The component contains two properties title and isAuthenticated. The second one of these is a flag that indicates whether the user has logged into the application. Right now, it is simply set to false. Two empty methods act as callbacks to trigger logging in or logging out. For now, I have left them empty, but you will be filling them in later on.


Complete the View

With this knowledge about the direction of dependency, you can update the View so that the buttons and forms perform actions on the ViewModel. Open src/app/notes/notes.component.html again and change the code to look like this.

<div fxLayout=“row” fxLayout.xs=“column” fxLayoutAlign=“center” class=“notes”>
<mat-list fxFlex=“100%” fxFlex.gt-sm=“20%”>
<mat-list-item _ngFor=‘let note of notes | async’>
<a (click)=“onSelectNote(note.id)”>
{{note.title}}
</a>
</mat-list-item>
</mat-list>
<mat-divider fxShow=“false” fxShow.gt-sm _[_vertical]=“true”></mat-divider>
<mat-divider fxShow=“true” fxShow.gt-sm=“false” _[_vertical]=“false”></mat-divider>
<div fxFlex=“100%” fxFlex.gt-sm=“70%” _ngIf=“!editNote” class=“note-container”>
<h3>{{currentNote.title}}</h3>
<p>
{{currentNote.text}}
</p>
<div fxLayout=“row” fxLayoutAlign=“space-between center” >
<button mat-raised-button color=“primary” (click)=“onEditNote()” _ngIf=“noteSelected()”>Edit</button>
<button mat-raised-button color=“warn” (click)=“onDeleteNote()” _ngIf=“noteSelected()”>Delete</button>
<button mat-raised-button color=“primary” (click)=“onNewNote()”>New Note</button>
</div>
</div>
<div fxFlex=“100%” fxFlex.gt-sm=“70%” *ngIf=“editNote” class=“form-container”>
<form [formGroup]=“editNoteForm” (ngSubmit)=“updateNote()”>
<mat-form-field class=“full-width”>
<input matInput placeholder=“Title” formControlName=“title”>
</mat-form-field>

  &lt;mat-form-field class="full-width"&gt;
    &lt;textarea matInput placeholder="Note text" formControlName="text"&gt;&lt;/textarea&gt;
  &lt;/mat-form-field&gt;
  &lt;button mat-raised-button color="primary"&gt;Update&lt;/button&gt;
&lt;/form&gt;

</div>
</div>

You can see (click) handlers in various places directly referring to the methods of the NotesComponent class. This means that the View needs to know about the ViewModel and its methods. The reason for reversing the dependency is the reduction of boilerplate code. There is a two-way data binding between the View and the ViewModel. The data in the View is always in sync with the data in the ViewModel.


Add Authentication to Your Angular App

A good application is not complete without proper user authentication. In this section, you will learn how to quickly add authentication to your existing Angular application. Okta provides single sign-on authentication which can be plugged into the app with just a few lines of code.

To start off, you will need a free developer account with Okta. In your favorite browser, open https://developer.okta.com, locate Create Free Account in the center of the page and click it. Simply fill in the form that appears with your details, accept the terms & conditions, and submit it by pressing Get Started. Once you have completed the registration you will be taken to the Okta dashboard. Here you can see an overview of all the applications registered with the Okta service.

Click on Add Application to register a new application. On the next screen that appears you will be given a choice of the type of application. The Single-Page Application is the right choice for your Angular app. On the page that follows, you will be shown the application settings. You will need to change the port number to 4200 when you are testing your application with ng serve.

That’s it. Now you should be seeing a Client ID which you will need later on. Now you are ready to include the authentication service into your code. Okta provides a convenient library for Angular. You can install it by running the following command in your application root directory.

npm install @okta/okta-angular@1.0.7 --save

Open app.module.ts and import the OktaAuthModule.

import { OktaAuthModule } from ‘@okta/okta-angular’;

Further down, in the same file add the following in the list of imports.

    OktaAuthModule.initAuth({
issuer: ‘https://{yourOktaDomain}/oauth2/default’,
redirectUri: ‘http://localhost:4200/implicit/callback’,
clientId: ‘{clientId}’
})

In this snippet, {clientId} needs to be replaced with the client ID that you just obtained in the Okta developer dashboard.

To protect specific routes from being accessed without a password you need to modify src/app/app-routing.module.ts. Add an import for OktaCallbackComponent and OktaAuthGuard.

import { OktaCallbackComponent, OktaAuthGuard } from ‘@okta/okta-angular’;

Next, add another route to the array of routes.

{ path: ‘implicit/callback’, component: OktaCallbackComponent }

The implicit/callback route will be called by Okta when the user has completed the login process. The OktaCallbackComponent handles the result and redirects the user to the page that requested the authentication process. To guard individual routes, you can now simply add OktaAuthGuard to that route, like this.

{ path: ‘notes’, component: NotesComponent, canActivate: [OktaAuthGuard] }

Remember that you have left the main application ViewModel un-implemented. Open src/app/app.component.ts again and add the following import to the top of the file.

import { OktaAuthService } from ‘@okta/okta-angular’;

Next, implement all the methods of the AppComponent class.

constructor(public oktaAuth: OktaAuthService) {}

async ngOnInit() {
this.isAuthenticated = await this.oktaAuth.isAuthenticated();
}

login() {
this.oktaAuth.loginRedirect();
}

logout() {
this.oktaAuth.logout(‘/’);
}

There is only one thing left to do. You can now add the Login and Logout buttons to the top bar. Open src/app/app.component.html and add these two lines inside the <mat-toolbar> element, after the closing </span>.

<button mat-button _ngIf=“!isAuthenticated” (click)=“login()”> Login </button>
<button mat-button _ngIf=“isAuthenticated” (click)=“logout()”> Logout </button>

The Login and Logout buttons are linked to the login() and logout() methods in the app.component.ts ViewModel. The visibility of these two buttons is determined by the isAuthenticated flag in the ViewModel.

That’s all there is to it! Now you have a complete application based on the MVVM architecture, complete with authentication. You can test it out by firing up the Angular test server in the application root directory.

ng serve

Open your browser and navigate to http://localhost:4200. You should see something like this.


Learn More

Angular and Nodejs Integration Tutorial

Full Stack Web Development with Angular and Spring MVC

Building Web App using ASP.NET Web API Angular 7 and SQL Server

Angular 7 Tutorial - Learn Angular 7 by Example

Build a Basic Website with ASP.NET MVC and Angular

Build a Simple Web App with Express, Angular, and GraphQL

Build a Basic CRUD App with Laravel and Angular

Full Stack Developers: Everything You Need to Know

MEAN Stack Tutorial MongoDB, ExpressJS, AngularJS and NodeJS

Angular 7 (formerly Angular 2) - The Complete Guide

Learn and Understand AngularJS

The Web Developer Bootcamp

Originally published at https://developer.okta.com

#angular #web-development

What is GEEK

Buddha Community

MVC in an Angular World
Christa  Stehr

Christa Stehr

1598940617

Install Angular - Angular Environment Setup Process

Angular is a TypeScript based framework that works in synchronization with HTML, CSS, and JavaScript. To work with angular, domain knowledge of these 3 is required.

  1. Installing Node.js and npm
  2. Installing Angular CLI
  3. Creating workspace
  4. Deploying your First App

In this article, you will get to know about the Angular Environment setup process. After reading this article, you will be able to install, setup, create, and launch your own application in Angular. So let’s start!!!

Angular environment setup

Install Angular in Easy Steps

For Installing Angular on your Machine, there are 2 prerequisites:

  • Node.js
  • npm Package Manager
Node.js

First you need to have Node.js installed as Angular require current, active LTS or maintenance LTS version of Node.js

Download and Install Node.js version suitable for your machine’s operating system.

Npm Package Manager

Angular, Angular CLI and Angular applications are dependent on npm packages. By installing Node.js, you have automatically installed the npm Package manager which will be the base for installing angular in your system. To check the presence of npm client and Angular version check of npm client, run this command:

  1. npm -v

Installing Angular CLI

  • Open Terminal/Command Prompt
  • To install Angular CLI, run the below command:
  1. npm install -g @angular/cli

installing angular CLI

· After executing the command, Angular CLI will get installed within some time. You can check it using the following command

  1. ng --version

Workspace Creation

Now as your Angular CLI is installed, you need to create a workspace to work upon your application. Methods for it are:

  • Using CLI
  • Using Visual Studio Code
1. Using CLI

To create a workspace:

  • Navigate to the desired directory where you want to create your workspace using cd command in the Terminal/Command prompt
  • Then in the directory write this command on your terminal and provide the name of the app which you want to create. In my case I have mentioned DataFlair:
  1. Ng new YourAppName

create angular workspace

  • After running this command, it will prompt you to select from various options about the CSS and other functionalities.

angular CSS options

  • To leave everything to default, simply press the Enter or the Return key.

angular setup

#angular tutorials #angular cli install #angular environment setup #angular version check #download angular #install angular #install angular cli

Obie  Beier

Obie Beier

1625660460

Learn MVC 5 & MVC Core with Angular

Learn MVC 5 & MVC Core with Angular @ 1990INR/30USD
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Following the Syllabus covered in this Package:
*Learn Angular 7.X, 8.X Step By Step.
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#mvc 5 & mvc #angular #mvc #mvc 5

Roberta  Ward

Roberta Ward

1593184320

Basics of Angular: Part-1

What is Angular? What it does? How we implement it in a project? So, here are some basics of angular to let you learn more about angular.

Angular is a Typescript-based open-source front-end web application platform. The Angular Team at Google and a community of individuals and corporations lead it. Angular lets you extend HTML’s syntax to express your apps’ components clearly. The angular resolves challenges while developing a single page and cross-platform applications. So, here the meaning of the single-page applications in angular is that the index.html file serves the app. And, the index.html file links other files to it.

We build angular applications with basic concepts which are NgModules. It provides a compilation context for components. At the beginning of an angular project, the command-line interface provides a built-in component which is the root component. But, NgModule can add a number of additional components. These can be created through a template or loaded from a router. This is what a compilation context about.

What is a Component in Angular?

Components are key features in Angular. It controls a patch of the screen called a view. A couple of components that we create on our own helps to build a whole application. In the end, the root component or the app component holds our entire application. The component has its business logic that it does to support the view inside the class. The class interacts with the view through an API of properties and methods. All the components added by us in the application are not linked to the index.html. But, they link to the app.component.html through the selectors. A component can be a component and not only a typescript class by adding a decorator @Component. Then, for further access, a class can import it. The decorator contains some metadata like selector, template, and style. Here’s an example of how a component decorator looks like:

@Component({
    selector: 'app-root',
    templateUrl: 'app.component.html',
    styleUrls: ['app.component.scss']
})

Role of App Module

Modules are the package of functionalities of our app. It gives Angular the information about which features does my app has and what feature it uses. It is an empty Typescript class, but we transform it by adding a decorator @NgModule. So, we have four properties that we set up on the object pass to @NgModule. The four properties are declarations, imports, providers, and bootstrap. All the built-in new components add up to the declarations array in @NgModule.

@NgModule({
declarations: [
  AppComponent,
],
imports: [
  BrowserModule,
  HttpClientModule,
  AppRoutingModule,
  FormsModule
],
bootstrap: [AppComponent]
})

What is Data Binding?

Data Binding is the communication between the Typescript code of the component and the template. So, we have different kinds of data binding given below:

  • When there is a requirement to output data from our Typescript code in the HTML template. String interpolation handles this purpose like {{data}} in HTML file. Property Binding is also used for this purpose like [property] = “data”.
  • When we want to trigger any event like clicking a button. Event Binding works while we react to user events like (event) = “expression”.
  • When we can react to user events and output something at the same time. Two-way Binding is used like [(ngModel)] = “data”.

image for understanding data binding

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navin prakash

1607084960

MVC Framework - Introduction

The Model-View-Controller (MVC) is an architectural style dividing an application into three main system elements: the model, the view, and the controller. Every one of these elements is designed to manage particular aspects of an application’s growth. To build scalable and extensible projects, MVC is one of the most commonly used industry-standard web design platforms.
MVC Elements
Following are the elements of MVC:
Model
All the data-related logic that the user works with corresponds to the Model part. It can represent either the data that is being transmitted between the elements of the View and Controller or some other data relevant to business logic. A customer object, for example, retrieves customer information from the database, manipulates it and updates its data back to the database, or utilizes this for information rendering.
View
For all of the application’s UI logic, the View element has been used. For example, all the UI elements such as text boxes, dropdowns, etc. That the final user communicates with will be included in the Customer’s perspective.
Controller
In order to manage all business rules and incoming requests, controllers serve as an interface between the Model And View elements, modify data using the Model component, and communicate with the Views to make the final performance. For example, the Customer Controller will handle all the Customer View interactions and inputs, and the database will be modified using the Customer Model. To display customer information, the same controller will be used.
ASP.NET MVC:
ASP.NET supports three main growth models: Web sites, Web Forms and MVC (Model View Controller).
ASP.NET MVC Features
ASP.NET MVC provides the following characteristics :

  • Ideal for designing applications that are complex but lightweight.
  • It offers an expandable and pluggable system that can be quickly replaced and customized. If you do not want to use the built-in Razor or ASPX View Engine, for instance, you can use some other third-party display engines or even customize existing ones.
  • Using the application’s elements-based architecture by logically breaking this into elements of the Organization, Display, and Controller. This allows developers to control the scope and focus on specific elements of large-scale projects.
  • The MVC structure enhances the app’s test-driven growth and testability since all elements can be programmed utilizing mock objects based on the interface. Hence, ASP.NET MVC Platform is suitable for Projects with a wide team of web designers.
  • Supports all the comprehensive ASP.NET features currently available, such as Authorization and Authentication, Master Pages, Data Linking, User Controls, Memberships, ASP.NET Routing, etc.
  • Don’t use View State definition (which is present in ASP.NET). This helps to create lightweight apps and allows the designers full power.
    You should also recognize the MVC System as a major structure built on top of ASP.NET that offers a wide range of added features focused on component-based creation and checking. MVC Training in Chennai is the best for freshers and professional workers. FITA is the NO.1 Training Institute to learn MVC Course in Chennai with certification. This Certification very usefu to get a job in the IT industry.

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Ayyaz Zafar

1624138795

Angular Material Autocomplete - Multiple Use Cases covered

Learn How to use Angular Material Autocomplete Suggestions Search Input. I covered multiple use cases.

Please watch this video. I hope this video would be helpful for you to understand it and use it in your projects

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