angular2-无法从Web服务获取数据

Question

第一次学习打字稿和angular2。 我正在创建一个仅执行GET和POST的通用服务，以便可以在整个应用程序中使用它。 我已经基于Dynamic Forms中 Angular的示例创建了我的应用

我的问题是我的“ QuestionService”正在使用“ ServerService”，但它抱怨this.ServerService.getData is not a function不是一个函数。

服务器服务

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);
    }

这是网址： https ： //plnkr.co/edit/InWESfa6PPVKE0rXcSFG？ p = preview

Answer 1

您需要做的是让Angular 将 ServerService注入到QuestionService ，就像在ServerService Http一样

@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);
    }
}

然后，您需要将两个服务都添加到providers数组

@NgModule({
  imports: [HttpModule],
  providers: [ServerService, QuestionService]
})
export class AppModule {}