Calling multiple services for a single component in Angular

Question

I have called a single service in angular but have never called multiple services. In the image I have attached the requirement is to add the client and group values into a table called clientGroup Xref. Also the client, Clientrole, ClientKey in different table (ClientService will do that) . I want to know how can I call clientservice and clientgroup Xref service both at the same time on create button click.

This is the code I tried so far 
import { Router } from '@angular/router';
import { AuthService } from './auth.service';
import {PESAuthService} from './pes_auth.service';
import { Component, OnInit, Injectable } from '@angular/core';
import { Http, Request, RequestMethod, RequestOptions, Headers, Response } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import {Client} from './../../shared/models/Client';

@Injectable()
export class ClientService implements OnInit {
    private appContent = 'application/json';
    private _router: Router;
   private baseUrl = 'http://localhost:5050/api/v1/';

  //Constructor to initialize authService to authenticate user, http to send the CRUD request and Router for the resource 
  constructor(private authService: AuthService, private http: Http,private router: Router,private pesauthservice: PESAuthService) {
  }
   ngOnInit() {
  }

  //For creating a user Client,Key,Firstname and lastName has to be passed 
//   created: Date
   create(client: string, clientkey: string, clientrole: string) :Observable<boolean> {
        //createAuthenticatedRequest is called before sending the Http request 
        let request = this.createAuthenticatedRequest(JSON.stringify({client: client, clientkey: clientkey, clientrole: clientrole}),RequestMethod.Post);

       return this.http.request(request).map(r=>{

            r.ok;
        }).catch((error: any) =>{
        return Observable.throw(error);
        });

   }
   update(id: number,client: string,  clientKey: string, clientRole: string, created: Date) :Observable<any> {

         let request = this.createAuthenticatedRequest(JSON.stringify(
             {id:id,client: client, clientKey: clientKey, clientRole: clientRole, created: created}),RequestMethod.Put,id.toString());
       return this.http.request(request).map(r=>{
            r.json;
            console.log(r);
        }).catch((error: any) =>{
            console.log(error);
        return Observable.throw(error);
        });

   }
   delete(client: string,  clientkey: string, clientrole: string, created: Date):Observable<boolean> {

     let request = this.createAuthenticatedRequest(JSON.stringify({client: client, clientkey: clientkey, clientrole: clientrole, created: created}),RequestMethod.Delete);
       return this.http.request(request).map(r=>{
            r.ok;
        }).catch((error: any) =>{
        return Observable.throw(error);
        });

   }

   //Read method takes an optional input id, If id is not passed to read it will get the entire list , else it will get the record with specified id
   read(id?: Number):Observable<any> {

         id = (id == undefined) ? 0 : id ;

        if (id >0)
            // Get single resouce from Collection
            var request = this.createAuthenticatedRequest(null,RequestMethod.Get, id.toString());
        else
           // Get the entire collection
             request = this.createAuthenticatedRequest(null,RequestMethod.Get, id.toString());

        return this.http.request(request).map(r=>{
           console.log(r.text());
            return  JSON.parse("[" + r.text() + "]")[0];
        }).catch((error: any) =>{
        return Observable.throw(error);
        });
   }



   //This method accepts json of the attribtes client,key,firstname and lastName and request method(Post/Get/Put/delete) and 
   //an optional parameter id , This method's return type is Request
   createAuthenticatedRequest(json : string, reqMethod: RequestMethod, optionalparam?: string) : Request{
        //checks if the user is authenticated user with authentication service method isAuthenticated
         if (this.authService.isAuthenticated()) {

             if( this.pesauthservice.isPESAuthenticated())
             {

            console.log('authenticated');
            //creating a request object with method,url and body consisting of client,key,firstname and lastName and optional parameter id
          optionalparam =(optionalparam==undefined || optionalparam =='0') ? "" : optionalparam;
            const request = new Request({
                method: reqMethod,
                url: this.baseUrl + 'clients/' + optionalparam +"",
                body: json
               });
               //request header Authorization is added to specify that the request has an authenticated token
            request.headers.append('Authorization', 'Bearer ' + this.pesauthservice.getToken());
            request.headers.append('Content-Type', this.appContent);
            request.headers.append('Accept', this.appContent);
            return request;
          }  
          else {
             console.log('notauthenticated');
             this._router.navigateByUrl('/login');
          } 
         }    

        else {
             console.log('notauthenticated');
             this._router.navigateByUrl('/login');
          } 

   }

}

Can someone tell me on the approach I should consider.

Answer 1

There are many ways you can do this.You can use Observable.forkjoin or Observable.merge

Object.forkJoin will wait until all requests are completed and then you can build a single list with this results;

Example for forkjoin

const allrequests = Observable.forkJoin(
  this.http.get('https://testdb1.com/.json').map((res: Response) => res.json()),
  this.http.get('https://testdb2.com/.json').map((res: Response) => res.json())
)
 allrequests.subscribe(latestResults => {
            const [ data_changes , data_all ] = latestResults;               
 });