Javascript 将多个文件上载到Firebase存储，所有上载完成后，订阅forkJoin

我正在制作一个上传表单，需要上传所有文件，当所有上传完成后，我想订阅它们并触发下一个操作

我当前的实现不起作用：

 private uploadImages(): Observable<Subscription> {
const uploadImages$: Subscription [] = [];
this.testResponse.answers.forEach(answer => {
  const filePath = `${answer.selectedImage.name.split('.').slice(0, -1).join('.')}_${new Date().getTime()}`;
  uploadImages$.push(this.testService.uploadPhoto(filePath, answer.selectedImage).subscribe((url: string) => {
      answer.imageUrl = url;
      delete answer.selectedImage;
      delete answer.id;
    }));
});
return forkJoin(uploadImages$);}

  public uploadPhoto(filePath: string, selectedImage?: UploadMetadata): Observable<string | UploadTaskSnapshot> {
return this.storage.upload(filePath, selectedImage).snapshotChanges().pipe(finalize(async () => this.getDownloadUrl(filePath))); }



  public getDownloadUrl(filePath: string): Observable<string> {
return this.storage.ref(filePath).getDownloadURL(); }

private uploadImages（）：可观察{
const uploadImages$：订阅[]=[]；
this.testResponse.answers.forEach（answer=>{
const filePath=`${answer.selectedImage.name.split（'.'）.slice（0，-1）.join（'.'）}{new Date（）.getTime（）}`；
uploadImages$.push（此.testService.uploadPhoto（文件路径、答案、选择图像）。订阅（（url:string）=>{
answer.imageUrl=url；
删除答案。选择图像；
删除answer.id；
}));
});
返回forkJoin（uploadImages$）；}
公共上传照片（文件路径：字符串，SelecteImage？：上传元数据）：可观察{
返回此.storage.upload（filePath，selectedImage）.snapshotChanges（）.pipe（finalize（async（）=>this.getDownloadUrl（filePath））；}
publicGetDownloadURL（文件路径：字符串）：可观察{
返回此.storage.ref（文件路径）.getDownloadURL（）；}

1.在管道中提供下载URL之前，“我如何等待”（finalize（async（）…）

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2.对于使用Angular将文件上载到Firebase，您是否有更好的实现方案？

希望这就是您试图实现的目标：

forkJoin(uploadImages$).pipe(
  map((photos) => {
    return photos.map(p => p.url);
  }),
  switchMap((photoUrls) => {
    return forkJoin(photoUrls.map(photoUrl => this.getDownloadUrl(photoUrl)));
  })
)
.subscribe((downloadUrls) => {
  console.log(downloadUrls);
});