"Can't adapt type" error on a Foreign key attribute with SQLAlchemy/PostGreSQL

I got a problem with PostGreSQL 8.4 and tables reflection. My metadata object seems to be ok (it has foreign keys, primary keys, every columns and tables). But when I try to associate an object to an another one through a Foreign key, I get : "sqlalchemy.exc.ProgrammingError: (ProgrammingError) can't adapt type 'EventParameters' 'INSERT INTO event (".

I'm using SQLAlchemy 0.6.3 (psycopg2 2.2.1) and PostGreSQL 8.4.5

Here, my code :

#! /usr/bin/env python 

from sqlalchemy import MetaData, create_engine 
from sqlalchemy.orm import mapper, sessionmaker 

class EventParameters(object): 
    pass 

class Event(object): 
    pass 

engine = create_engine('postgresql://postgres:toto@127.0.0.1:5432/renass') 
metadata = MetaData() 
metadata.reflect(bind=engine) 
Session = sessionmaker(bind=engine) 
session = Session() 
mapper(EventParameters, metadata.tables['eventparameters']) 
mapper(Event, metadata.tables['event']) 

ep = EventParameters() 
ep.publicid = 'test' 

e = Event() 
e.publicid = 'test' 
e.eventparametersid=ep 

session.add(e) 
session.commit()

and my database :

CREATE TABLE EventParameters ( 
    id SERIAL PRIMARY KEY, 
    publicID varchar(255) UNIQUE NOT NULL, 
    description varchar(255), 
    creationInfo_agencyID varchar(64), 
    creationInfo_agencyURI varchar(255), 
    creationInfo_author varchar(128), 
    creationInfo_authorURI varchar(255), 
    creationInfo_creationTime time, 
    creationInfo_version varchar(64) 
); 

CREATE TABLE Event ( 
    id SERIAL PRIMARY KEY, 
    eventParametersID integer NOT NULL REFERENCES EventParameters(id), 
    publicID varchar(255) UNIQUE NOT NULL, 
    preferredOriginID integer, 
    preferredMagnitudeID integer, 
    preferredFocalMechanismID integer, 
    type EventType, 
    typeCertainty EventTypeCertainty, 
    creationInfo_agencyID varchar(64), 
    creationInfo_agencyURI varchar(255), 
    creation开发者_运维知识库Info_author varchar(128), 
    creationInfo_authorURI varchar(255), 
    creationInfo_creationTime time, 
    creationInfo_version varchar(64) 
);

It seems that SQLAlchemy don't recognize the attribute "eventparametersid" as a relationship ...

Thank you in advance Fabien

To make your code working you should change the mapper invocation for the Event class to include the mapping between the two classes

mapper(Event, metadata.tables['event'], properties={
    'eventparameters': relation(EventParameters)
})

then use that column to assign the EventParameters instance

ep = EventParameters()
ep.publicid = 'test'

e = Event()
e.publicid = 'test'
e.eventparameters = ep