[Sqlalchemy-tickets] Issue #3480: abstractconcretebase regression with setting up columns via name vs. attribute name (zzzeek/sqlalchemy)

[Mike B. <iss...@bi...>]

New issue 3480: abstractconcretebase regression with setting up columns via name vs. attribute name
https://bitbucket.org/zzzeek/sqlalchemy/issues/3480/abstractconcretebase-regression-with

Mike Bayer:

without the "key" workarounds uncommented, this fails:

```
#!python

from sqlalchemy.ext.declarative import declarative_base, AbstractConcreteBase
from sqlalchemy.ext.declarative.api import declared_attr
from sqlalchemy.orm.mapper import configure_mappers
from sqlalchemy.orm.session import Session
from sqlalchemy.sql.schema import Column, ForeignKey
from sqlalchemy.sql.sqltypes import Date, String, Integer

Base = declarative_base()


class Company(Base):
    __tablename__ = 'companies'
    id = Column(Integer, primary_key=True)


class Document(object):
    date = Column(Date)
    documentType = Column('documenttype', String) #, key="documentType")


class ContactDocument(AbstractConcreteBase, Base, Document):
    contactPersonName = Column('contactpersonname', String) #, key="contactPersonName")
    salesPersonName = Column(String)
    sendMethod = Column('sendmethod', String) #, key="sendMethod")

    @declared_attr
    def company_id(self):
        return Column(ForeignKey('companies.id'))


class Offer(ContactDocument):
    __tablename__ = 'offers'

    id = Column(Integer, primary_key=True)


class SalesOrder(ContactDocument):
    __tablename__ = 'orders'

    id = Column(Integer, primary_key=True)


configure_mappers()
session = Session()
query = session.query(ContactDocument)
print(query)
```

```
#!


  File "/Users/classic/dev/sqlalchemy/lib/sqlalchemy/orm/mapper.py", line 627, in __init__
    self._configure_properties()
  File "/Users/classic/dev/sqlalchemy/lib/sqlalchemy/orm/mapper.py", line 1284, in _configure_properties
    self._configure_property(key, prop, False)
  File "/Users/classic/dev/sqlalchemy/lib/sqlalchemy/orm/mapper.py", line 1525, in _configure_property
    prop = self._property_from_column(key, prop)
  File "/Users/classic/dev/sqlalchemy/lib/sqlalchemy/orm/mapper.py", line 1679, in _property_from_column
    "attribute." % (key, self, c))
sqlalchemy.exc.ArgumentError: When configuring property 'documentType' on Mapper|ContactDocument|pjoin, column 'documenttype' is not represented in the mapper's table. Use the `column_property()` function to force this column to be mapped as a read-only attribute.
```