flutter - 当 uploadTask 完成但将图像上传到存储时，getDownloadURL 返回 null

Question

我试图上传到存储的图像是成功的，但是当我想使用上传的图像将 URL 存储到数据库中时，由于某种原因它返回 null。

Future<String> _uploadPic(String docRef, File file) {
FirebaseStorage _storage = FirebaseStorage.instance;
auth.currentUser().then((userID) async{
  StorageReference reference = _storage.ref().child(userID).child(docRef);
  StorageUploadTask uploadTask = reference.putFile(file);
  String downloadURL = (await uploadTask.onComplete).ref.getDownloadURL().toString();

  return downloadURL;
});

}

日志:

I/flutter (17507): debug: the uri is: null

Answer 1

Future<dynamic> _uploadPic(String docRef, File file) {

    FirebaseStorage _storage = FirebaseStorage.instance;

    // you need to return the result...
    return auth.currentUser().then((userID) async {
      StorageReference reference = _storage.ref().child(userID).child(docRef);
      StorageUploadTask uploadTask = reference.putFile(file);
      return (await uploadTask.onComplete).ref.getDownloadURL();
    });

}