angular2 - cannot get data from web service - web-services

Question

Learning typescript & angular2 for the first time. I'm creating a generic service that just does GET and POST so that I can use it in the entire app. I've based my app on Angular's example from Dynamic Forms
My issue is that my "QuestionService" is using a "ServerService" but it is complaining that this.ServerService.getData is not a function isnt a function.
ServerService
import { Injectable } from '#angular/core';
import { Http, Response } from '#angular/http';
import { Observable } from 'rxjs/Observable';
#Injectable()
export class ServerService {
private apiUrl = 'app/users.json';
constructor (private http: Http) {}
getData (): Observable<any>[] {
return this.http.get(this.apiUrl)
.map(this.extractData)
.catch(this.handleError);
}
QuestionService
import { ServerService } from './server.service';
#Injectable()
export class QuestionService implements OnInit{
errorMessage: string;
mode = 'Observable';
questions: QuestionBase<any>[];
ServerService = ServerService;
ngOnInit() { this.getQuestions(); }
getQuestions(ServerService: ServerService<any>){
console.log('getQuestions');
console.log(this.ServerService.getData());
this.ServerService.getData()
.subscribe(
questions => this.questions = questions,
error => this.errorMessage = <any>error);
}
Here is the url: https://plnkr.co/edit/InWESfa6PPVKE0rXcSFG?p=preview

Answer 1

What you need to do is let Angular inject the ServerService into the QuestionService, just like are doing with the Http inside the ServerService
#Injectable()
export class QuestionService implements OnInit{
constructor(private serverService: ServerService) {}
ngOnInit() { this.getQuestions(); }
getQuestions(){
this.serverService.getData()
.subscribe(
questions => this.questions = questions,
error => this.errorMessage = <any>error);
}
}
Then you need to add both services to the providers array
#NgModule({
imports: [HttpModule],
providers: [ServerService, QuestionService]
})
export class AppModule {}