CRUD Operations in Angular 7

Nishu Goel Software Engineer, IBM | Udemy Author | Angular Developer @DcoustaWilson Blog: https://nishugoel.wordpress.com HELLO!

GitHub Repository https://github.com/NishuGoel/CRUDwithAngular Blog post on Building a CRUD Application with Angular https://www.c-sharpcorner.com/article/building-a-crud-application- with-angular/

CRUD?

Fake a back-end Server?

Three ways - Return data from local File - Use local JSON file - Use Angular-in-memory-web-api

Angular in-memory-web-api

AGENDA ❑ Getting the data from the in memory data store ❑ Reading this data ❑ Creating the data ❑ Updating the data ❑ Deleting the data

❑ Setting up the in-memory-web-api npm install angular-in-memory-web-api --save-dev ❑ Importing it in the module for the data class @NgModule({ imports: [ BrowserModule, InMemoryWebApiModule.forRoot(UserData) ] )

Using the in-memory-web-api ❑ Create the entity class export class User { constructor ( public id = 0, public name= '', public model= 0, ) {}} createDb(){ } ❑ Providing the method to create data in the class

Data ready, Let’s perform HTTP operations! - Create Service - Inject HttpClient service to perform the HTTP operations - Refer to the created API Perform Create, Read, Update, Delete

Create Service ng generate service constructor(private http: HttpClient) { } Inject http service apiurl = 'api/Users’; headers = new HttpHeaders().set('Content-Type', 'application/json').set('Accept', 'application/json'); httpOptions = { headers: this.headers }; Use the data Import required statements import { HttpClient, HttpHeaders, HttpParams } from '@angular/common/http'; import { Observable, throwError } from 'rxjs'; import { tap, catchError, map } from 'rxjs/operators'; import { User } from './User';

Read Operation Using http.get() method

getUsers(): Observable { return this.http.get(this.apiurl).pipe( tap(data => console.log(data)), catchError(this.handleError) ); } In the service In the Component Users: User[] = []; constructor(private dataservice: DataService) { } ngOnInit() { this.getUsers(); } getUsers() { this.dataservice.getUsers().subscribe(data => { this.Users = data; }); } }

Create Data Using http.post()

In the Service addUser (User: User): Observable { return this.http.post(this.apiurl, User, this.httpOptions).pipe( tap(data => console.log(data)), catchError(this.handleError) ); } On the Component addUser() { this.dataservice.addUser(this.UserFormGroup.val ue).subscribe(data => { this.User = data; console.log(this.User); }); this.getUsers();

Update Data Using http.put()

In the Service updateUser (user: User): Observable { return this.http.put(this.apiurl, User, this.httpOptions).pipe( tap(data => console.log(data)), catchError(this.handleError) ); } On the Component updateUser() { this.dataservice.getUser(this.idtoupdate).subscribe(data => { this.UserToUpdate = data; this.UserToUpdate.model = 'updated model'; this.dataservice.updateUser(this.UserToUpdate).subscribe(data1 => { this.getUsers(); }); });

Delete Data Using http.delete()

In the Service deleteUser (id: number): Observable { const url = `${this.apiurl}/${id}`; return this.http.delete(url, this.httpOptions).pipe( catchError(this.handleError) ); } On the Component deleteUser() { this.dataservice.deleteUser(this.idtodelete).subscribe(data => { this.getUsers(); }); }

Stackblitz Demo https://stackblitz.com/github/NishuGoel/CRUDwithAngular Thank You!