google-drive api: creation of subfolder under root instead of the parent folder ID provided

Question

I am not sure what I am doing wrong here. The code below shows I am requesting to create a subfolder under a specific parent ID... yet the folder gets created in the root of the drive instead. Any help immensely appreciated!

def _makeFolder(service, folderName, parentId):
_fileMetadata = {
    'name'      : folderName,
    'mimeType'  : CONST_MIME_FOLDER,
    'parents'   : parentId
}
_newFolderId = service.files().create(body=_fileMetadata, fields='id').execute()
return(_newFolderId.get('id'))

Answer 1

You should add list to the parents field:

'parents'   : [parentId]