从可观察的订阅中返回承诺值 [英] Return promise value from observable subsciption

问题描述

是否有机会从getDataFromApi()的helpMe函数值返回?到目前为止，每次我调用此函数时，我都会得到"null"值.

Is there any chance to return from helpMe function value from getDataFromApi() ? So far every time i call this function i get "null" value.

       async function helpMe() {
            let promise = null;
            let sub = someService.someObservable.subscribe(async () => {
               promise = await getDataFromApi()
            })
            subscriptions.push(sub)
            return promise;
        }

第一个目标是我需要将预订存储在全局子数组中.第二个目标是当我收到状态为400的响应时-我不想打开模式.只有当我得到200并且一切都很好时，我才希望打开模式.

The first goal is i need to store subscription in global sub array. The second goal is when i get response with status 400 - I dont want to open modal. Only when i get 200 and everything is allright i want modal to be opened.

function async load() {
  const promise = await helpMe();
  openModal();
}

推荐答案

您可以只使用普通的rxjs而不是使用异步/等待功能. switchmap运算符可能在这里为您提供帮助:

Instead of using async/await feature, you could just go with plain rxjs. The switchmap operator might help you here:

public helpMe()
{
  return this.someService.someObservable.pipe(
    switchMap(result =>
    {
      return someDataFromApi();
    }),
    tap(resultFromApi => {
      // ... do something with `resultFromApi` from `someDataFromApi`.
    }),
  ).toPromise();
}

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