set uppercase versions of any string choices as attributes on the Cho…

…iceProperty => easier to get choice->index mapping than c2i()

  -- Thanks to Nick Johnson for this suggestion too :)

__init__.py

@@ -530,16 +530,22 @@ class ChoiceProperty(db.IntegerProperty):
   >>> ChoiceModel.gql("WHERE a_choice = :1", green).count()
   1
   """
-  def __init__(self, choices, *args, **kwargs):
+  def __init__(self, choices, make_choice_attrs=True, *args, **kwargs):
     """Constructor.
 
     Args:
       choices: A non-empty list of 2-tuples of the form (id, choice). id must be
         the int to store in the database.  choice may be any hashable value.
+      make_choice_attrs: If True, the uppercase version of each string choice is
+        set as an attribute whose value is the choice's int representation.
     """
     super(ChoiceProperty, self).__init__(*args, **kwargs)
     self.index_to_choice = dict(choices)
     self.choice_to_index = dict((c,i) for i,c in self.index_to_choice.iteritems())
+    if make_choice_attrs:
+      for i,c in self.index_to_choice.iteritems():
+        if isinstance(c, basestring):
+          setattr(self, c.upper(), i)
 
   def get_choices(self):
     """Gets a list of values which may be assigned to this property."""