angular2 - 无法从网络服务获取数据

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，以便我可以在整个应用程序中使用它。我的应用基于 Angular 来自 Dynamic Forms

的示例

我的问题是我的 "QuestionService" 使用的是 "ServerService" 但它抱怨 this.ServerService.getData is not a function 不是函数。

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);
  }

问题服务

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);
    }

这里是url：https://plnkr.co/edit/InWESfa6PPVKE0rXcSFG?p=preview

Answer 1

你需要做的是让 Angular 将 ServerService 注入 ServerService 到 QuestionService 中，就像对 Http 在 ServerService

里面

@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);
    }
}

然后您需要将这两个服务添加到 providers 数组

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