HttpModule : Making HTTP Request

First you need to install HttpModule using npm’s command

npm install -g @angular/http@latest

Demo Below :

app.component.html

<div class="container">
  <div class="row">
    <div class="col-xs-12 col-sm-10 col-md-8 col-sm-offset-1 col-md-offset-2">
      <input type="text" #serverName>
      <button class="btn btn-primary" (click)="onAddServer(serverName.value)">Add Server</button>
      <br><br>
      <button class="btn btn-primary" (click)="onSave()">Save Serves</button>
      <button class="btn btn-primary" (click)="onGet()">Get Serves</button>
      <hr>
      <ul class="list-group" *ngFor="let server of servers">
        <li class="list-group-item">{{ server.name }} (ID: {{ server.id }})</li>
      </ul>
    </div>
  </div>
</div>

app.component.ts

import { ServersService } from './servers.service';
import { Component } from '@angular/core';
import { Response } from '@angular/http';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  constructor(private serversService: ServersService) {}
  servers = [
    {
      name: 'Testserver',
      capacity: 10,
      id: this.generateId()
    },
    {
      name: 'Liveserver',
      capacity: 100,
      id: this.generateId()
    }
  ];
  onAddServer(name: string) {
    this.servers.push({
      name: name,
      capacity: 50,
      id: this.generateId()
    });
  }
  onSave(){
    console.log('On Save called');
    this.serversService.storeServers(this.servers)
      .subscribe(
        (response) => console.log(response),
        (error) => console.log(error)
        );
  }
  onGet(){
    console.log('On Get Called');
    this.serversService.getServers().subscribe(
      (response: Response) => {
        const data = response.json();
        console.log(data);
      },
      (error) => console.log(error)
    );
  }
  private generateId() {
    return Math.round(Math.random() * 10000);
  }
}

app.component.css

.container {
  margin-top: 50px;
}

app.module.ts

import { ServersService } from './servers.service';
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpModule } from '@angular/http';

import { AppComponent } from './app.component';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    HttpModule
  ],
  providers: [ServersService],
  bootstrap: [AppComponent]
})
export class AppModule { }

servers.service.ts

import { Injectable } from '@angular/core';
import { Http, Headers } from '@angular/http';
import 'rxjs/Rx';

@Injectable()
export class ServersService{
  constructor(private http: Http){}
  storeServers(servers: any[]) {
    const headers = new Headers({'Content-Type' : 'application/json'})
    return this.http.put('https://angulardemo-64fa2.firebaseio.com/data.json', servers,
    {headers: headers});
  }
  getServers(){
    return this.http.get('https://angulardemo-64fa2.firebaseio.com/data.json');
  }
  storeServersPost(servers: any[]) {
    const headers = new Headers({'Content-Type' : 'application/json'})
    return this.http.post('https://angulardemo-64fa2.firebaseio.com/data.json', servers,
    {headers: headers});
  }
}

Final

app.component.css

.container {
  margin-top: 50px;
}

app.component.html

<div class="container">
  <div class="row">
    <div class="col-xs-12 col-sm-10 col-md-8 col-sm-offset-1 col-md-offset-2">
      <h1>{{ appName | async }}</h1>
      <input type="text" #serverName>
      <button class="btn btn-primary" (click)="onAddServer(serverName.value)">Add Server</button>
      <br><br>
      <button class="btn btn-primary" (click)="onSave()">Save Servers</button>
      <button class="btn btn-primary" (click)="onGet()">Get Servers</button>
      <hr>
      <ul class="list-group" *ngFor="let server of servers">
        <li class="list-group-item">{{ server.name }} (ID: {{ server.id }})</li>
      </ul>
    </div>
  </div>
</div>

app.component.ts

import { Component } from '@angular/core';
import { Response } from '@angular/http';

import { ServerService } from './server.service';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  appName = this.serverService.getAppName();
  servers = [
    {
      name: 'Testserver',
      capacity: 10,
      id: this.generateId()
    },
    {
      name: 'Liveserver',
      capacity: 100,
      id: this.generateId()
    }
  ];
  constructor(private serverService: ServerService) {}
  onAddServer(name: string) {
    this.servers.push({
      name: name,
      capacity: 50,
      id: this.generateId()
    });
  }
  onSave() {
    this.serverService.storeServers(this.servers)
      .subscribe(
        (response) => console.log(response),
        (error) => console.log(error)
      );
  }
  onGet() {
    this.serverService.getServers()
      .subscribe(
        (servers: any[]) => this.servers = servers,
        (error) => console.log(error)
      );
  }
  private generateId() {
    return Math.round(Math.random() * 10000);
  }
}

app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpModule } from '@angular/http';

import { AppComponent } from './app.component';
import { ServerService } from './server.service';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    HttpModule
  ],
  providers: [ServerService],
  bootstrap: [AppComponent]
})
export class AppModule { }

server.service.ts

import { Injectable } from '@angular/core';
import { Headers, Http, Response } from '@angular/http';
import 'rxjs/Rx';
import { Observable } from 'rxjs/Observable';

@Injectable()
export class ServerService {
  constructor(private http: Http) {}
  storeServers(servers: any[]) {
    const headers = new Headers({'Content-Type': 'application/json'});
    // return this.http.post('https://udemy-ng-http.firebaseio.com/data.json',
    //   servers,
    //   {headers: headers});
    return this.http.put('https://udemy-ng-http.firebaseio.com/data.json',
      servers,
      {headers: headers});
  }
  getServers() {
    return this.http.get('https://udemy-ng-http.firebaseio.com/data')
      .map(
        (response: Response) => {
          const data = response.json();
          for (const server of data) {
            server.name = 'FETCHED_' + server.name;
          }
          return data;
        }
      )
      .catch(
        (error: Response) => {
          return Observable.throw('Something went wrong');
        }
      );
  }
  getAppName() {
    return this.http.get('https://udemy-ng-http.firebaseio.com/appName.json')
      .map(
        (response: Response) => {
          return response.json();
        }
      );
  }
}