angular - 如果条件在 RxJS 中为真，我可以跳过所有后续运算符链吗

Question

是否有可能在 RxJS 5.5 中使用一些运算符来实现条件以跳过所有后续运算符并发出一些值(false)？例如，在这个 ng 服务方法中，如果 response.length === 0，我会绕过一堆 .map 链并立即提供 false 值:

getProjectDrivers(projectId): Observable<any> {
  return this.http.get('someUrl').pipe(
    // if (response.length === 0) { return false; and skip whole operator chain bellow}
    map((response: ProjectDriver[]) => response.filter((projectDriver: ProjectDriver) => projectDriver.streamName !== "AllRevenueStreamTotals")),
    map((response: ProjectDriver[]) => command => ({})
  )
)
.catch(this.handleError);

Answer 1

我想你总是可以玩 switchMap

  return this.http.get('someUrl').pipe(
    switchMap(response => {
      if (!response.length) {
        return of(null);
      } else {
        return of(result).pipe(
          map((response: ProjectDriver[]) => response.filter((projectDriver: ProjectDriver) => projectDriver.streamName !== "AllRevenueStreamTotals")),
          map((response: ProjectDriver[]) => command => ({}))
        )
      }
    }
  )