Select directory relative to a specific file

[SinZ163]

A common pattern when a known file structure is known ahead of time is to ask the user to select a well known file in the file structure and use that to obtain the directory.

This is to provide a level of validation so the user doesn't select a folder that won't match the correct file structure and used a lot in mod managers.

Example, there is some executable file MyGame.exe and you want to add files to the same folder, rather than having a directory picker and the user potentially picking any folder, they have a filepicker instead that only accepts MyGame.exe as input.

[jencibacsi]

@mkruisselbrink :

Another argument (and a solution proposal):

I can call the showOpenFilePicker() method with a FileSystemFileHandle in the "startIn" parameter - the dialog starts in the directory of the file (in which the file resides).
There is getFileHandle() method (fileHandle = await directoryHandle . getFileHandle(name)) with which the caller can get back a FileSystemFileHandle to a file by name in the given directory.
And there is a getDirectoryHandle() method (subdirHandle = await directoryHandle . getDirectoryHandle(name)) which returns a handle for a directory by name in the directory represented by directoryHandle.

Feature request:
directoryHandle = await fileHandle . getDirectoryHandle()
A method which returns a FileSystemDirectoryHandle which points to the directory in which the file resides...

[dslee414]

The workaround mentioned above of using startIn parameter might work for this use case. If the goal is to get the parent directory given a file handle, whatwg/fs#38 discusses a similar feature request.