触发循环内的同步调用，直到两个api调用成功，然后下一次迭代需要以角度6开始

Question

[使用以下代码尝试过，不要等到响应成功之前，调用成功就跳到下一个迭代。要求：成功两次调用api（POST / PATCH）之后需要进行下一次迭代

 for (item of data) {
  A(item)

}
A(value) {
  const resp = this.post(url, {
      'rationale': value['rationale']
    })
    .mergeMap(tempObj => {
      value['detail'] = tempObj['id']
      return this.patch(url, value['extid'], value)
    })
    .subscribe()
}

Answer 1

// This must be executed inside an async function
for (item of data) {
  await A(item)
}

async A(value) {
  const resp = await this.post(url, {
      'rationale': value['rationale']
    })
    .mergeMap(tempObj => {
      value['detail'] = tempObj['id']
      return this.patch(url, value['extid'], value)
    }).toPromise();
}

Answer 2

const resp$ = from(data).pipe(
  concatMap(value => this.post(url, { 'rationale': value['rationale'] }).pipe(
    switchMap(tempObj => {
      value['detail'] = tempObj['id']
      return this.patch(url, value['extid'], value)
    })
  ))
)

我使用switchMap而不是mergeMap表示未使用mergeMap同时运行多个Observable的功能。

Answer 3