// this action uploads the collection of files to the hard drive and returns the upload result
public async Task <IActionResult> Upload(IFormFileCollection uploads, string folderId)
{
if (!_fileSystemService.CheckEditAccess(_fileSystemService.GetFolderById(folderId), User.FindFirstValue(ClaimTypes.NameIdentifier)))
{
throw new StatusCodeException($"You don't have access to folder with ID = {folderId}.", StatusCodes.Status403Forbidden);
}
List <ElementVM> elements = (await _fileSystemService.UploadFiles(uploads, _fileSystemService.GetFolderById(folderId))).ToList();
return(new ObjectResult(elements));
}