google apps script - Converting string to web-safe Base64 format

Question

I am testing how to update user picture using the Admin SDK Directory Service with Google Apps Scripts with the following function:

function updatePhoto(){
  var fileId = 'XXXXXXXXXXXXXXXXXXX';
  var b = DocsList.getFileById(fileId).getBlob();
  var encoded = Utilities.base64Encode(b.getBytes());

  encoded = encoded.replace(///g,'_').replace(/+/g,'-').replace(/=/g,'*');
  AdminDirectory.Users.Photos.update({
    "photoData": encoded },'harry.potter@abc.edu.hk');
}

However, it doesn't always work. Whenever there is padding in the base64 encoded string, it fails. Referring to Google's document (https://developers.google.com/admin-sdk/directory/v1/reference/users/photos/update), I am a bit confused with the descriptions. It says:

1. The equals sign (=) character is replaced with the asterisk (*).
2. For padding, the period (.) character is used instead of the RFC-4648 baseURL definition which uses the equals sign (=) for padding. This is done to simplify URL-parsing.

What should be actually done? (=) is used for padding in Base64. So, should I use (*) or (.)? I did try to replace (=) with (.) but no luck.

Can anyone help?

---

It is so strange. It works when i do not replace (=).

function updatePhoto(){
  var fileId = 'XXXXXXXXXXXXXXXXXXX';
  var b = DocsList.getFileById(fileId).getBlob();
  var encoded = Utilities.base64Encode(b.getBytes());

  encoded = encoded.replace(///g,'_').replace(/+/g,'-');
  AdminDirectory.Users.Photos.update({
    "photoData": encoded },'harry.potter@abc.edu.hk');

}

Answer 1

The API requires you to use URL-safe base64 encoding. After doing the base64 encoding, try replacing / with _ and + with -. Details at:

https://developers.google.com/admin-sdk/directory/v1/reference/users/photos/update