NG4 - http-POST = POST Data Access service

NG4 - http-POST = POST Data Access service
=========================================
import { Component,Output,OnInit,Input, EventEmitter } from '@angular/core'

postProduct.component.ts
------------------------

@Component({
selector:'postHttp',
styleUrls: ['./postHttp.scss'],
templateUrl: './postHttp.html',
})

export class GetHttpComponent implements OnInit{

...
constructor(private productService: ProductService) { }
...
postProduct(id: number): void {
this.productService.postProduct(id)
.subscribe(
(product: IProduct) => this.onProductRetrieved(product),
// ---> Instead of this (data:any)=>{ if(data.success){ //true } else { //false }}
(error: any) => this.errorMessage= <any>error
);
}

@Injectable()
exportclassProductService{
privatebaseUrl= 'www.myWebService.com/api/products';
constructor(privatehttp: Http) { }
createProduct(product: IProduct): Observable<IProduct> {
letheaders = newHeaders({ 'Content-Type': 'application/json'});
letoptions = newRequestOptions({ headers: headers });
return this.http.post(this.baseUrl, product, options)
.map(this.extractData).catch(this.handleError);
}
}
}

postProduct.service.ts
----------------------
...
import { Http, Response} from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
...
@Injectable()
exportclassProductService{
privatebaseUrl= 'www.myWebService.com/api/products';
constructor(privatehttp: Http) { }
createProduct(product: IProduct): Observable<IProduct> {
letheaders = newHeaders({ 'Content-Type': 'application/json'});            
letoptions = newRequestOptions({ headers: headers });
return this.http.post(this.baseUrl, product, options)
.map(this.extractData);
}
}

private extractData(res: Response) {
    let body = res
    return body || {} ;
  }
   private handleError (error: any) {
    // In a real world app, we might use a remote logging infrastructure
    // We'd also dig deeper into the error to get a better message
    let errMsg = (error.message) ? error.message :
      error.status ? `${error.status} - ${error.statusText}` : 'Server error';
    console.error(errMsg); // log to console instead
    return Observable.throw(errMsg);
  }