Allow to save files without using byte data

[ekuleshov]

Currently the FilePicker.saveFile(..) API requires passing the bytes parameter containing fill file data to save. For large files (200..400mb video files aren't uncommon) it puts a lot of pressure to device memory.

It would be great if the .saveFile(..) offered alternative ways to provide the file data: stream, a file path (the temp path may already be used by the platform code) or maybe XFile. Also see share_plus and file_saver plugins.

[daniJimen]

@ekuleshov actually, in the latest version, we are using xfile now for that propose in beta version https://github.com/miguelpruivo/flutter_file_picker/releases/tag/v12.0.0-beta.5

[ekuleshov]

@ekuleshov actually, in the latest version, we are using xfile now for that propose in beta version https://github.com/miguelpruivo/flutter_file_picker/releases/tag/v12.0.0-beta.5

@daniJimen as far as I can see internally it still reads file into the byte data and passes bytes over the method channel. That is a big memory pressure on low-end device.

For large files an opposite would be much more preferable - e.g. copy or move file to a location where it can be accessed from both Flutter code and platform native code. When possible, it should also use move file instead of copying its content (don't think it will work for Android because of SAF).

[scottandrewzip]

I second this. Don't require bytes. We have our own save mechanism and like to just know if they picked the location and name or cancelled. This was in previous betas. Bytes should be optional.

[github-actions]

This issue is stale because it has been open for 7 days with no activity.

[ekuleshov]

Please don't close this issue. We really need a solution to save large files on all Flutter target platforms.

[scottandrewzip]

This needs to be fixed. This breaks our saving mechanism we don't write to bytes but to a large zip archive.

[vicajilau]

Correcting a comment further up this thread: there is no XFile parameter in saveFile() today.

• bytes: Uint8List is still required on every platform (Dart API, platform interface, and every platform implementation).
• There is no path based native streaming. On Linux/Windows/macOS the plugin does File(path).writeAsBytes(bytes) with bytes already fully materialized in Dart before the call even reaches native code.

So this is still an open problem, not something already solved in a recent beta.

This is a real, non-trivial API change (it touches the public saveFile() signature on every platform), so leaving it open as a feature to design properly rather than a quick fix.

[narumi147]

About saveFile, the wiki should update whether saveFile write data or not, currently the wiki said it not write, but it seem some platforms write file. Not sure all platforms write data or not.