javascript - 如何通过构造函数异步调用注入(inject)服务，Angular 2

Question

这就是问题所在:我有一个在构造函数中发出 HTTP 请求的服务:

    constructor(public http: Http, public geolocation: Geolocation) {
        this.http = http;
        this.geolocation = geolocation;
        //Http request... this will set variable forecast of the class when complete.
        this.getForecast(16);
    }

然后我将该服务注入(inject)到这样的组件中:

    constructor(public connector: ApiConnector) {
         this.forecast = connector.forecast;
    }

如果我像这里一样尝试在组件装饰器上使用组件类的 forecast 成员:

@Component({
    selector: 'app',
    directives: [MainForecast, DailyForecast],
    template: `
        <main-forecast [main-weather]="forecast"></main-forecast>
        <daily-forecast [weather-list]="forecast.list"></daily-forecast>
    `,
})

I get an error, "Cannot read property 'list' of undefined in..."

是否有可能在组件构造函数中使用 promises？

Answer 1

Angular2 建议在 ngOnInit 中而不是在构造函数中做繁重的工作。

ngOnInit 是一个生命周期钩子(Hook)/事件。