Merge pull request #307 from eywalker/master

Fix hick up with `help()` and better user response handling

Author: dimitri-yatsenko

datajoint/user_relations.py

@@ -61,6 +61,8 @@ def table_name(cls):
         """
         :returns: the table name of the table formatted for mysql.
         """
+        if cls._prefix is None:
+            raise AttributeError('Class prefix is not defined!')
         return cls._prefix + from_camel_case(cls.__name__)
 
     @ClassProperty

datajoint/utils.py

@@ -22,7 +22,7 @@ def user_choice(prompt, choices=("yes", "no"), default=None):
     valid = False
     while not valid:
         response = input(prompt + ' [' + choice_list + ']: ')
-        response = response if response else default
+        response = response.lower() if response else default
         valid = response in choices
     return response