I have also experienced problems with this exception.Here is a simple
example:
import sqlalchemy
import sqlalchemy.orm as orm
engine = sqlalchemy.create_engine('sqlite:///:memory:', echo=True)
metadata = sqlalchemy.MetaData()
users_table = sqlalchemy.Table('users', metadata,
sqlalchemy.Column('id', sqlalchemy.Integer,
primary_key=True),
sqlalchemy.Column('name', sqlalchemy.String),
sqlalchemy.Column('fullname', sqlalchemy.String),
sqlalchemy.Column('password', sqlalchemy.String)
)
metadata.create_all(engine)
metadata.bind = engine
class User(object):
pass
orm.mapper(User, users_table)
MySession = orm.sessionmaker(autoflush=True, autocommit=False)
session = MySession()
user = User()
user.name = "ed"
user.fullname = "Ed Jones"
user.password = "password"
session.add(user)
session.commit()
session.close()
print user.name
The last print statement fails with the "attribute refresh operation
cannot proceed" exception with the 0.5.2 version. The corresponent
code for 0.4.5 works fine.
What I would like to be able to is to keep on working with detached
objects like the user object in the code above , in a manner where the
objects attribute values are the same as they were when the session
was closed, i.e. without further database queries (and certainly
without exceptions!). If there was some way to ensure that all
database attributes on the object were loaded but not modifiable, it
could solve the problem. In my current application I use the
get_session extension to return the ScopedSession instance in order to
ensure that I can access attributes but I would prefer that the
objects were properly detached but still funcionable.
Any ideas as to what I could do?
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