如何return到函数级别？

Question

我有一个函数 loadMessages，我想要它 return 一个 Observable。

  loadMessages(chatId: string): Observable<Message[]> {
    console.log('1');

    this.autorun(() => {
      const handle = this.subscribe('messages', chatId);

      if (handle.ready()) {
        console.log('2');

        const messages = Messages.find().fetch();
        return Observable.of(messages);  // here return is not for this function, which is useless
      }
    });

    console.log('3');  // I don't want this line run immediately

    // I wish I can return here, but I cannot
  }

如何才能return到函数级别？

还有，现在顺序是1 -> 3 -> 2，有没有办法运行 1 -> 2，等我拿到数据？

Answer 1

您可以尝试这样的操作：

loadMessages(chatId: string): Observable<Message[]> {
  console.log('1');

  return Observable.create(observer => {
    this.autorun(() => {
      const handle = this.subscribe('messages', chatId);

      if (handle.ready()) {
        console.log('2');

        const messages = Messages.find().fetch();
        observer.next(messages)
      }
    });
  });
}

这里是非常简单的例子http://plnkr.co/edit/GADtB8QCTnNubtRu9SFv?p=preview

如何return到函数级别？

How to return to the function level?

meteor

typescript

angular

rxjs5

angular2-meteor