[chaley]

That error is harmless, caused by the template dialog not having a real book to work with. It will work when it us run "for real" -- when sending to the device.

This version removes the error.

python:
def evaluate(book, context):
	import os
	from calibre.library import current_library_path

	fmt_metadata = book.get('format_metadata')
	if fmt_metadata:
		for v in fmt_metadata.values():
			# A calibre format name is roughly "author/title (id)/title - author.extension"
			# We want to return the last segment, stripping off the author and title 
			# directory names and the extension, leaving just the basename of the book file
			f = v['path']
			return f[f.rfind(os.sep)+1:f.rfind('.')] 
	else:
		return 'title - author'