The following setup lets you

  • choose a file from your computer to upload
  • upload it to a defined folder on google drive
  • inserts the link to the current cell

To get it working:

  1. find out the id of the google drive folder you want your attachments be saved (in the example below this is 0B0uw1JCogWHuc29FWFJMWmc3Z1k)
  2. in the spreadsheet where you want to upload the file: do Tools→Script Editor.. and paste the script below. Be sure to replace the id with your folders id

Update 2014: Made it working with the new sheets
Update 2016-05 Fixed the script thanks to the comments by Fede and Dov (DocsList.getFolderId was not working any more)

  // upload document into google spreadsheet
  // and put link to it into current cell

  function onOpen(e) {
    var ss = SpreadsheetApp.getActiveSpreadsheet()
    var menuEntries = [];
    menuEntries.push({name: "File...", functionName: "doGet"});
    ss.addMenu("Attach ...", menuEntries);

  function doGet(e) {
    var app = UiApp.createApplication().setTitle("upload attachment into Google Drive");
    var form = app.createFormPanel().setId('frm').setEncoding('multipart/form-data');
    var formContent = app.createVerticalPanel();

    // these parameters need to be passed by form
    // in doPost() these cannot be found out anymore
    formContent.add(app.createHidden("activeCell", SpreadsheetApp.getActiveRange().getA1Notation()));
    formContent.add(app.createHidden("activeSheet", SpreadsheetApp.getActiveSheet().getName()));
    formContent.add(app.createHidden("activeSpreadsheet", SpreadsheetApp.getActiveSpreadsheet().getId()));
    return app;

  function doPost(e) {
    var app = UiApp.getActiveApplication();
    var fileBlob = e.parameter.thefile;
var doc = DriveApp.getFolderById('0B0uw1JCogWHuc29FWFJMWmc3Z1k').createFile(fileBlob);
    var label = app.createLabel('file uploaded successfully');

    // write value into current cell
    var value = 'hyperlink("' + doc.getUrl() + '";"' + doc.getName() + '")'
    var activeSpreadsheet = e.parameter.activeSpreadsheet;
    var activeSheet = e.parameter.activeSheet;
    var activeCell = e.parameter.activeCell;
    var label = app.createLabel('file uploaded successfully');
    return app;