AbstractConcreteAbstraction doesn't know that it's "mapped" until other mappers configure themselves. In the absence of such an event, call sqlalchemy.orm.configure_mappers() when all subclasses of AbstractConcreteAbstraction have been declared to force this process to occur.
On Feb 27, 2013, at 6:57 PM, Derek Litz <litzoma...@gmail.com> wrote: > Python 2.7.3 (default, Jan 4 2013, 14:06:23) > [GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))] on > darwin > Type "help", "copyright", "credits" or "license" for more information. > >>> import sqlalchemy > >>> print sqlalchemy.__version__ > 0.8.0b2 > > Below is the code I was able to use to reproduce a problem I was having. > Here is the stack trace: > > Traceback (most recent call last): > File "test.py", line 48, in <module> > print session.query(AbstractConcreteAbstraction).all() > File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", > line 1079, in query > return self._query_cls(entities, self, **kwargs) > File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line > 115, in __init__ > self._set_entities(entities) > File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line > 122, in _set_entities > entity_wrapper(self, ent) > File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line > 2949, in __init__ > "expected - got '%r'" % (column, ) > sqlalchemy.exc.InvalidRequestError: SQL expression, column, or mapped entity > expected - got '<class '__main__.AbstractConcreteAbstraction'>' > > The workaround I discovered while trying to reproduce is to simply > instantiate a subclass... am I missing something? > > from sqlalchemy.engine import Engine > from sqlalchemy import event > from sqlalchemy import (Column, Integer, Unicode, DateTime, ForeignKey, > Boolean, Numeric, Time) > > > # Taken from http://docs.sqlalchemy.org/ru/latest/dialects/sqlite.html > @event.listens_for(Engine, "connect") > def set_sqlite_pragma(dbapi_connection, connection_record): > cursor = dbapi_connection.cursor() > cursor.execute("PRAGMA foreign_keys=ON") > cursor.close() > > > from sqlalchemy import create_engine > from sqlalchemy.ext.declarative import (declarative_base, declared_attr, > AbstractConcreteBase) > from sqlalchemy.orm import sessionmaker > > engine = create_engine('sqlite:///test.db') > sqlite = declarative_base(bind=engine) > get_session = sessionmaker(bind=engine) > session = get_session() > > from sqlalchemy.schema import UniqueConstraint > > > class AbstractConcreteAbstraction(AbstractConcreteBase, sqlite): > __table_args__ = (UniqueConstraint('derpa', > 'derp'),) > id = Column(Integer, primary_key=True) > derpa = Column(Integer) > derp = Column(Integer) > > > class ConcreteConcreteAbstraction(AbstractConcreteAbstraction): > __tablename__ = u'cca' > __mapper_args__ = {'polymorphic_identity': 'ccb', > 'concrete': True} > > print AbstractConcreteAbstraction > > sqlite.metadata.create_all() > > # DOES NOT WORK WITHOUT!!! > # ConcreteConcreteAbstraction(derpa=2, derp=2) > > print session.query(AbstractConcreteAbstraction).all() > print session.query(ConcreteConcreteAbstraction).all() > > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sqlalchemy+unsubscr...@googlegroups.com. > To post to this group, send email to sqlalchemy@googlegroups.com. > Visit this group at http://groups.google.com/group/sqlalchemy?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
