Angular 1.x and Angular2 Blog: Send a HTTP request in angular2 Service using Typescript

In this post we are going to see how to send a HTTP request in Angular2 service and access the data from the response using the observable API

First we have to create a Model based on the response type, so that we are creating a interface for that, then we have to create a service which will make a HTTP call.

export interface IUser{
    id:number;
    name:string;
    username:string;
    email:string;
    address:IAddress;
    phone:string;
    website:string;
    company:ICompany;
    albums:IAlbum[];    
}

export interface ICompany{
    name:string;
    catchPharse:string;
    bs:string;
}

export interface IAddress{
    street:string;
    suite:string;
    city:string;
    zipcode:string;
    geo:IGeo;
}

export interface IGeo{
    lat:string;
    lon:string;
}

export interface IAlbum{
    albumId:number;
    id:number;
    title:string;
    url:string;
    thumbnailUrl:string;
}

Then we have to create a service which have the HTTP api has a dependency , The instance of the HTTP will be created in the constructor.

    import { Injectable } from '@angular/core';
    import { Http, Response } from '@angular/http';
    import { Observable } from 'rxjs/observable';
    import { IUser,IAlbum } from './user';
    import 'rxjs/add/operator/catch'
    import 'rxjs/add/operator/map';
    import 'rxjs/add/operator/do';

    @Injectable()
    export class DataService{

    private data:string[]=["Rajesh","suresh","ramu"];
    private url:string = "http://jsonplaceholder.typicode.com/users";

    constructor(private _http:Http){

    }

    getEmployees(): Observable<IUser[]>{
    return this._http.get(this.url)
    .map((response:Response)=><IUser[]>response.json())
    .do(data=>console.log("All : "+JSON.stringify(data)))
    .catch(this.HandleError);
    }

    getAlbums(id):Observable<any>{

    return this._http.get("http://jsonplaceholder.typicode.com/photos?albumId="+id)
    .map((response:Response)=><IAlbum[]>response.json())
    .do(data=>console.log("album "+JSON.stringify(data)))
    .catch(this.HandleError);       

    }


    private HandleError(error:Response){
        console.log(error);
        return Observable.throw(error.json().error || "server error");
    }

    addEmployee(name){
        this.data.push(name);
    }

    }

Next we have to invoke the call from inside the component , here we have to subscribe the request because return type of the method is a observable of particular type, in observable to get the response we have to subscribe , in subscribe we have three parameter, success, error, complete.

import { Component } from '@angular/core';
import { DataService } from './data.service';
import { IUser } from './user'

@Component({
    selector:'employee',
    template:`
    <div style="display:inline-block;width:400px;vertical-align:top">
        <h1>Employee </h1>
        <div>
            <input type="text" #emp />
            <button (click)="addEmployee(emp.value)" 
                class="btn btn-sm btn-primary">Add Emp</button>
            <button (click)="getEmployee()" 
                class="btn btn-sm btn-primary">Get Employees</button>
            <div style="margin-top:20px">
            <ul class="list-group" style="display:-webkit-box;overflow-x:scroll">
                <li class="panel list-group-item-primary" 
                *ngFor="let e of employees" style="list-style:none;">
                <div class="panel panel-default">
                <div class="panel-heading">
                    <h3 class="panel-title">{{e.username}}</h3>
                </div>
                <div class=""panel-body>
                    <div class="text-info" style="padding:5px;">{{e.name}} 
                    <span class="btn btn-sm btn-primary" 
                        (click)="getAlbum(e.id)">Get Album</span></div>
                    <div class="text-primary" style="padding:5px;"> 
                        {{e.address.city}},{{e.address.zipcode}}</div>
                    <div *ngIf="e.albums">
                    <ul class="list-group">
                    <li class="list-group-item" *ngFor="let alb of e.albums">
                        <div class="panel panel-default">
                            <div class="panel-heading">{{alb.title}}</div>
                            <div class=""panel-body>                       
                                <img [src]="alb.thumbnailUrl" />
                            </div>
                        </div>
                    </li>
                    </ul>
                    </div>
                </div>
                </div>
                </li>
            </ul>
            </div>
        </div>
    </div>
    `   
})
export class EmployeeComponent
{
    employees:IUser[];
  
    constructor(private dataservice:DataService){
        
    }

    addEmployee(employeeName)
    {
        this.dataservice.addEmployee(employeeName);
    }

    getEmployee(){
        this.dataservice.getEmployees()
        .subscribe(
            customer=>this.employees=customer,
            error=>console.log("error"+error)
            );
       
    }

    getAlbum(id){
        this.dataservice.getAlbums(id)
        .subscribe(
            albums=>this.employees.find(emp=>emp.id==id).albums = albums
            );
    }
}

Next thing we have to inject the module in to root module then start the app to run

    import { NgModule } from '@angular/core';
    import { BrowserModule } from '@angular/platform-browser';
    import { FormsModule } from '@angular/forms';
    import { HttpModule } from '@angular/http';
    
    import { BaseRequestOptions, Http, Headers } from '@angular/http';
    import { webformComponent } from './Component/web.component'
    import { PrintComponent } from './Component/print.component';
   
    import { EmployeeComponent,StudentComponent } from './employee.component'
    import { DataService } from './data.service';

    @NgModule({
        imports: [BrowserModule,
                  FormsModule,
                  HttpModule],
        exports: [],
        declarations: [webformComponent,
                       PrintComponent,        
                       EmployeeComponent],
        providers:[DataService],
        bootstrap:[webformComponent]
    })
    export class AppModule { 

    }

    import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
    import { AppModule } from './app.module';
    import { HelloModule } from './hello.module'

    const platform = platformBrowserDynamic();

    let moduleref = platform.bootstrapModule(AppModule);