在 Observable 上使用 await 时，我应该使用什么来代替 toPromise()? [英] What should I use instead of toPromise() when using await on an Observable?

问题描述

此页面说"toPromise 已被弃用！(RxJS5.5+)" 但我最近一直在 AngularFire2 中使用它(当我只想要一个结果时)，如下所示:

This page says "toPromise has been deprecated! (RxJS 5.5+)" but I've been using it lately with AngularFire2 (when I only want one result) like this:

const foo = await this.afs.doc(`docPath`).valueChanges().toPromise();

我不应该这样做吗?如果不是，await 替代方案是什么?

Should I not be doing this? If not, what is the await alternative?

更新:

在下面的答案之后我改变了这个:

After the answer below I've changed this:

const foo = await this.afs.doc(`docPath`).valueChanges().toPromise();

...至此:

const foo = await (new Promise(resolve => this.afs.doc(`docPath`).valueChanges().pipe(first()).subscribe(result => resolve(result))));

有人可以向我解释这是如何改进吗?！对我来说好像倒退了一步.

Could someone please explain to me how this is an improvement?! Seems like a step backward to me.

推荐答案

你应该把管道放在后面！

You just should put after pipe!

   .pipe(take(1)).toPromise

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