[Sqlalchemy-tickets] Issue #3331: sqlalchemy 1.0.0b1 does not allow getting an declared_attr from declarative object (zzzeek/sqlalchemy)

[Pieter M. <iss...@bi...>]

New issue 3331: sqlalchemy 1.0.0b1 does not allow getting an declared_attr from declarative object
https://bitbucket.org/zzzeek/sqlalchemy/issue/3331/sqlalchemy-100b1-does-not-allow-getting-an

Pieter Mulder:

The following code works without any problems in sqlalchemy 0.9.9 but fails in 1.0.0b1:

```
#!python

import sqlalchemy as sa
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.declarative import declared_attr


Base = declarative_base()


class Abstract1(object):

    @declared_attr
    def __tablename__(cls):
        return cls.__name__.lower()


class Concrete1(Abstract1, Base):
    id = sa.Column(sa.Integer, primary_key=True)


Abstract1.__tablename__
Concrete1.__tablename__

```

The exception:


```
#!
<ipython-input-8-1445e04c4c3b> in <module>()
----> 1 Concrete1.__tablename__

/home/pieter/.virtualenvs/proigia_encryption/lib/python2.7/site-packages/sqlalchemy/ext/declarative/api.pyc in __get__(desc, self, cls)
    180         except KeyError:
    181             raise exc.InvalidRequestError(
--> 182                 "@declared_attr called outside of the "
    183                 "declarative mapping process; is declarative_base() being "
    184                 "used correctly?")

InvalidRequestError: @declared_attr called outside of the declarative mapping process; is declarative_base() being used correctly?

```