http - 使用 HTTP Angular

Question

我正在尝试使用 Angular 发出一个简单的 HTTP 请求，但我一直收到此错误:

Property 'http' does not exist on type 'WorksService'.

import {Injectable}     from 'angular2/core';
import {Http, HTTP_PROVIDERS, Response} from 'angular2/http';
import {Observable}     from 'rxjs/Observable';

export class Work {

  constructor(public id: number, public name: string) { }

}


@Injectable()
export class WorksService {

 constructor (private http: Http) {}

 private _WorksUrl = 'api/projects';  // URL to web api

 getHeroes () {
  return this.http.get(this._WorksUrl)
                .map(res => <Work[]> res.json().data)
                .catch(this.handleError);
 }
 private handleError (error: Response) {
   // instead of just logging it to the console
   console.error(error);
   return Observable.throw(error.json().error || 'Server error');
  }
}

Answer 1

我猜你自己实例化了服务。您需要通过依赖注入(inject)来获取它，以便 Angular2 将直接提供 http 实例。

为此，只需在引导应用程序时或在使用该服务(直接或间接)的组件的 providers 属性中添加服务即可。

bootstrap(AppComponent, [ HTTP_PROVIDERS, WorksService ]);

或

bootstrap(AppComponent, [ HTTP_PROVIDERS ]);

(...)

@Component({
  (...)
  providers: [ WorksService ]
})
export class SomeComponent {}

然后要注入(inject)它，您可以这样做:

@Component({
  (...)
})
export class SomeComponent {
  constructor(private service WorksService) {
    this.service.getHeroes().subscribe(
      (data) => {
        (...)
      });
  }
}