angular - 如何让执行等待 forkJoin 结果

Question

如何让以下代码等待 forkJoin 执行，以便我可以从 bulkRequest 返回结果？

  constructor(private http: Http) {
    let results = this.bulkRequest(this.get("https://jsonplaceholder.typicode.com/posts/1"),
      this.get("https://jsonplaceholder.typicode.com/posts/1"),
      this.get("https://jsonplaceholder.typicode.com/posts/1"));

    console.log("results");
  }

  get(url: string): Observable<any> {
    return this.http.get(url).map(response => response.json());
  }

  bulkRequest(...sources: SubscribableOrPromise<any>[]): any[] {
    let results: any[];

    Observable.forkJoin(
        sources
    ).subscribe(response => {
        console.log("responses");
        results = response;
    }, error => {
      console.log("error: " + error.toString());
    },
    () => {
      console.log("finally");
    });

    return results;
  }

目前我得到以下控制台输出并且 results 变量是 undefined:

results
responses
finally

Observable 会执行，如果我在 console.log("results") 行中放置一个断点，我会在 Network 选项卡中将它们全部视为 Pending。

请联系:http://plnkr.co/edit/2wb72kw7S3wYUUwwwi8h?p=preview

Answer 1

return Observable.forkJoin( ...

并移除

return results;

无法等待可观察对象。您需要在调用 bulkRequest() 的地方订阅返回的 observable。