从
Angular2 access global service without including it in every constructor我已经抓住代码,稍微修改为：
@Injectable()
export class ApiService {
constructor(public http: Http) {}
get(url: string) {
return http.get(url);
}
}
@Injectable()
export abstract class BaseService {
constructor(protected serv: ApiService) {}
}
@Injectable()
export class MediaService extends BaseService {
// Why do we need this?
constructor(s: ApiService) {
super(s)
}
makeCall() {
this.serv.get("http://www.example.com/get_data")
}
}
NoProviderError {message: “No provider for ApiService! (App ->
MediaService -> ApiService)”,stack: “Error: DI Exception↵
我已经在https://plnkr.co/edit/We2k9PDsYMVQWguMhhGl创建了一个Plunkr的代码
有谁知道是什么原因导致这个错误？
您还需要在providers属性中定义ApiService.
原文链接：https://www.f2er.com/angularjs/140592.html@Component({
selector: 'my-app',providers: [MediaService,ApiService],// <-----
template: `
<div>
<h2>Hello {{name}}</h2>
</div>
`,directives: []
})
export class App {
constructor(mediaService: MediaService) {
this.name = 'Angular2'
console.log('start');
mediaService.makeCall();
}
}
这是因为注射器依赖组件.如果您想了解有关如何将服务注入服务的更多详细信息,可以看看这个问题：
> What’s the best way to inject one service into another in angular 2 (Beta)?
