Flutter - 返回 UploadTask 而是返回 TaskSnapshot答案

【问题标题】：Flutter - returning UploadTask returns TaskSnapshot insteadFlutter - 返回 UploadTask 而是返回 TaskSnapshot
【发布时间】：2020-10-28 13:59:31
【问题描述】：

自上次flutter升级Flutter 1.22.2

  Future uploadImageToStore(path, {String remotePath = "receiptImages"}) async {
    Io.File _image = Io.File(path);
    String fileName = Path.basename(_image.path);
    print("uploadImageToStore " + path);
    if (await _image.exists()) {
      final Reference storageReference =
          FirebaseStorage.instance.ref().child(remotePath + "/" + fileName);
      final UploadTask uploadTask = storageReference.putFile(_image);

      return uploadTask;
    } else {
      print("image does not exit");
    }
  }

它不返回UploadTask，而是返回TaskSnapshot

使用此方法的代码使用UploadTask 设置监听器：

final UploadTask uploadTask = await this.uploadImageToStore(
    newReceipt['mergedImgPath']['path'],
    remotePath: "receiptMergedImage");

uploadTask.events.listen((event) async {
  this.updateReceiptProgress(event, newReceipt.key, receiptBloc);
});

以前版本的代码，现在可以编译但抛出运行时异常：

Unhandled Exception: type 'TaskSnapshot' is not a subtype of type 'UploadTask'

如何解决此问题以使用新的颤振版本？

【问题讨论】：

标签： flutter

【解决方案1】：

这是我的解决方案：

将uploadImageToStore 更改为：

  Future<TaskSnapshot> uploadImageToStore(path,
      {String remotePath = "receiptImages", void onData(event)}) async {
    Io.File _image = Io.File(path);
    String fileName = Path.basename(_image.path);
    print("uploadImageToStore " + path);
    if (await _image.exists()) {
      final Reference storageReference =
          FirebaseStorage.instance.ref().child(remotePath + "/" + fileName);
      final UploadTask uploadTask = storageReference.putFile(_image);
      uploadTask.events.listen(onData);

      return uploadTask;
    } else {
      print("image does not exit");
    }
  }

即添加onData参数并将其用于uploadTask.events.listen(onData);

如下使用：

final TaskSnapshot taskSnapshot = await this.uploadImageToStore(
    newReceipt['mergedImgPath']['path'],
    remotePath: "receiptMergedImage", 
    onData: (event) async {
      this.updateReceiptProgress(event, newReceipt.key, receiptBloc);
    });

虽然它解决了问题，但我仍然不确定为什么原始代码停止工作

【讨论】：

【解决方案2】：

对我有用的是改变：

return uploadTask;

到

return Future.value(uploadTask);

【讨论】：