saveFile() not working

[BoHellgren]

I tried the new saveFile API in 4.1.0:

Future<void> saveSettings(ArtWork artWork) async {
  String fileName = artWork.title + '.diy';
  String outputFile = await FilePicker.platform.saveFile(
    dialogTitle: 'Please select an output file:',
    fileName: fileName,
  );
  print('output file name $outputFile');
}

But I get this error message, both running on Android and on Web:

errors.dart:202 Uncaught (in promise) Error: UnimplementedError: saveFile() has not been implemented.
    at Object.throw_ [as throw] (errors.dart:251)
    at saveFile (file_picker.dart:156)
    at saveFile.next (<anonymous>)
    at runBody (async_patch.dart:84)
    at Object._async [as async] (async_patch.dart:123)
    at file_picker_web.FilePickerWeb.__.saveFile (file_picker.dart:150)
    at saveSettings (VM28 widgetsweb.dart.lib.js:438)
    at saveSettings.next (<anonymous>)
    at runBody (async_patch.dart:84)
    at Object._async [as async] (async_patch.dart:123)
    at Object.saveSettings (VM28 widgetsweb.dart.lib.js:436)
    at VM28 widgetsweb.dart.lib.js:410
    at Generator.next (<anonymous>)
    at async_patch.dart:45
    at _RootZone.runUnary (zone.dart:1687)
    at _FutureListener.thenAwait.handleValue (future_impl.dart:160)
    at handleValueCallback (future_impl.dart:767)
    at Function._propagateToListeners (future_impl.dart:796)
    at _Future.new.[_completeWithValue] (future_impl.dart:602)
    at async._AsyncCallbackEntry.new.callback (future_impl.dart:640)
    at Object._microtaskLoop (schedule_microtask.dart:40)
    at _startMicrotaskLoop (schedule_microtask.dart:49)
    at async_patch.dart:166

I also tested pickFiles and it works as expected:

Future<void> restoreSettings(ArtWork artWork) async {
  FilePickerResult pickerResult = await FilePicker.platform.pickFiles();
  if (pickerResult.files.first != null){
    String fileName = pickerResult.files.first.name;
    print('picker fileName $fileName');
    Uint8List fileBytes = pickerResult.files.first.bytes;
    print('picker fileBytes $fileBytes');
  }
}

Why do I get the "not implemented" message on saveFile?

D:\>flutter --version
Flutter 2.5.1 • channel stable • https://github.com/flutter/flutter.git
Framework • revision ffb2ecea52 (3 days ago) • 2021-09-17 15:26:33 -0400
Engine • revision b3af521a05
Tools • Dart 2.14.2

[miguelpruivo]

CC: @philenius

[philenius]

hey @BoHellgren, I'm sorry to disappoint you, but this functionality is only supported on desktop platforms (Linux, macOS, and Windows). In issue #799, @miguelpruivo and I thought that there is no need to implement this functionality on Android / iOS / web.

The docs of saveFile() contain one tiny sentence mentioning these circumstances 😉 :

  /// Opens a save file dialog which lets the user select a file path and a file
  /// name to save a file.
 ... blablabla
  /// This method is only available on desktop platforms (Linux, macOS &
  /// Windows).
... blablabla
  /// Returns [null] if aborted. Returns a [Future<String?>] which resolves to
  /// the absolute path of the selected file, if the user selected a file.
  Future<String?> saveFile({
    String? dialogTitle,
    String? fileName,
    FileType type = FileType.any,
    List<String>? allowedExtensions,
  })
...

[miguelpruivo]

@philenius sorry, my bad, didn't noticed that the OP was referring to Android.

Yes, @BoHellgren, like @philenius pointed out, this isn't supported on mobile devices as of now. I'm not sure if it will be even supported at all. I'm sorry for any inconvenience.