def get_keys(self, lst):
pk_name = self.get_pk_name()<EOL>if self.is_pk_composite():<EOL><INDENT>return [[getattr(item, pk) for pk in pk_name] for item in lst]<EOL><DEDENT>else:<EOL><INDENT>return [getattr(item, pk_name) for item in lst]<EOL><DEDENT>
return a list of pk values from object list