GAE db.Model getting property instead of a string value

Question

I have a db.Model which has a string property on it, email_type. Now I've the values for type defined in a readonly class. When I save this to the datastore I get the string instead of "Register", it also raises a BadValueError. How do I get it to save as a string, not as a property.

Here's the (slimmed down) code:

class EmailTypes(object):

    def __init__(self):
        self.__reg = "Register"
        self.__news = "NewsLetter"

    @property
    def Register(self):
        return self.__reg

    @property
    def NewsLetter(self):
        return self.__news

class Email(db.Model):
    to = db.StringProperty()
    email_type = db.StringProperty()


class Example(object)

    def do_stuff(self):
        e = Email()
        e.to = '[email protected]'
        # This should be saving as 'Register' not a ref to the objects address
        e.email_type = EmailTypes().Register

do = Example()
do.do_stuff()

Answer 1

e.email_type = EmailTypes().Register

That only gives you the method/property object. You should call it like this to get the value:

e.email_type = EmailTypes().Register()

Answer 2

What happens if you change your EmailTypes class to look like this:

class EmailTypes(object):
    Register = 'Register'
    NewsLetter = 'NewsLetter'

and use it like:

e.email_type = EmailTypes.Register

Does that make your simplified example work?