Find the folder ID of the current Google Apps spreadsheet

Question

In a script bound to a Google Sheet, how can I learn the ID (not the name) of the folder containing the current sheet? I want to do this:

var files = DriveApp.getFolderById('0B9momRZYw4DVTlJVeXNpX25BemM').getFiles();

but using a variable that represents the folder ID, like this:

var files = DriveApp.getFolderById(folderId).getFiles();

The problem is I cannot figure out how to obtain the parent folder's ID. I realize the current sheet may reside in several different folders (mine doesn't), but surely there is some way to get the ID of the folder?

Answer 1

This is quite straightforward using DriveApp getParents() method. Code goes like this :

function getParentFolder(){
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var file = DriveApp.getFileById(ss.getId());
  var folders = file.getParents();
  while (folders.hasNext()){
    Logger.log('folder name = '+folders.next().getName());
  }
}

Use folders.next().getId() to get the folder(s) ID(s).