What should I use instead of toPromise() when using await on an Observable?

问题

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();

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

UPDATE:

After the answer below I've changed this:

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

...to this:

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

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

回答1:

You just should put after pipe!

   .pipe(take(1)).toPromise

来源：https://stackoverflow.com/questions/51677405/what-should-i-use-instead-of-topromise-when-using-await-on-an-observable