On Tuesday, December 27, 2011 7:22:03 AM UTC-8, Michael Bayer wrote:
>
>
> On Dec 27, 2011, at 4:54 AM, Arturo Sevilla wrote:
>
> > Thanks for the code, your example runs without a problem.
> >
> > I've managed to "locate" the error. In reality it doesn't have to do
> with InstrumentedList. The problem occurs when beaker pickle.load()s from
> its cache file (a pickled object in a file).
> > I get the following exception (which makes beaker stop loading the
> session): AttributeError: 'User' object has no attribute
> '_sa_instance_state'
>
> That means User wasn't mapped when the object was created. This is one of
> many reasons I've been encouraging declarative as the standard way to go
> these days, so that you can't create a class without it being mapped at
> once.
>
I tried doing class_mapper(User) before the creation of the object.
According to the docs if such class is not mapped, then an exception should
be raised. I never got such exception so I assume the class is mapped
before any (mapped) instance is created. This makes sense as the mapper is
called when the import is done.
> >
> > If I try to load the file directly I get the same result.
> >
> > I've been trying to google such error but all I get the reference to is
> that orm.mapper() should be run in the thread or process that is loading
> the pickled object. I tried loading "manually" (in a python console) my
> mappers and the trying to unpickle the object without success.
>
> mapper() needs to be run in the process, and should be run in the "main"
> thread before any worker threads are spawned. It should ideally be part of
> module import, or at the very least a "right after import" initialization
> step.
>
> The User object itself must be mapped before the original one is ever
> created, before it is ever pickled in the first place. If it doesn't have
> a state, it means it was not mapped when pickled.
>
> >
> > I cannot (at the moment) include a code example because it is a medium
> sized pylons project. I know that this was working with version 0.6, with
> orm.synonym; the main difference is that now I use @hybrid_property and
> version 0.7.4.
>
> I can't think of a way that @synonym by itself would affect this.
> Changing back to @synonym in 0.7.4 does what ?
>
I don't think so either. However I noticed that the error occurred when
SQLAlchemy was restoring the '_parents' attribute of a MutableComposite
property that the User class has. I have read the docs, and I know that
'_parents' should be popped from __dict__ in __getstate__()
In fact, I took your code and modified to include a MutableComposite
property in the tables. I don't get my exception, but I do get an error
while loading from the pickled version (in a similar fashion with my
original problem).
from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.mutable import MutableComposite
class User(object):
def __init__(self, companies, name):
self.companies = companies
self.com_name = name
class Company(object):
pass
class NameComposite(MutableComposite):
def __init__(self, name, last_name):
self.name = name
self.last_name = last_name
def __composite_values__(self):
return self.name, self.last_name
def __getstate__(self):
copy_dict = self.__dict__.copy()
copy_dict.pop('_parents', None)
return copy_dict
def __setattr__(self, key, value):
object.__setattr__(self, key, value)
self.changed()
def __eq__(self, other):
return isinstance(other, NameComposite) and \
other.name == self.name and \
other.last_name == self.last_name
def __ne__(self, other):
return not self.__eq__(other)
metadata = MetaData()
user_table = Table('user', metadata,
Column('id', Integer, primary_key=True),
Column('name', String(100), nullable=False),
Column('last_name', String(100), nullable=False),
)
company_table = Table('company', metadata,
Column('id', Integer, primary_key=True),
Column('user_id', Integer, ForeignKey('user.id'))
)
mapper(User, user_table, properties={
'com_name': composite(NameComposite,
user_table.c.name,
user_table.c.last_name
),
'companies': relationship(Company, backref='_admin')
})
mapper(Company, company_table)
e = create_engine("sqlite://", echo=True)
metadata.create_all(e)
s = Session(e)
user = User(companies=[Company(), Company(), Company()],
name=NameComposite('name', 'last name'))
s.add_all([
user
])
s.commit()
import cPickle
dumped = cPickle.dumps(user)
assert cPickle.loads(dumped).id == 1 # ERROR
I get "sqlalchemy.orm.exc.DetachedInstanceError: Instance <User at
0x1405dd0> is not bound to a Session; attribute refresh operation cannot
proceed"
As the error informs me, I tried by doing s.add(user) and s.merge(user)
before the dumps() call without success.
If it is of any use my original error occurs in here:
File
"/lib/python2.6/site-packages/SQLAlchemy-0.7.4-py2.6-linux-x86_64.egg/sqlalchemy/ext/mutable.py",
line 413, in unpickle
val._parents[state.obj()] = key
File "/usr/lib/python2.6/weakref.py", line 249, in __setitem__
self.data[ref(key, self._remove)] = value
File "/model/base.py", line 230, in __eq__ # This are
my files (I have a base class for all my entities with a __eq__ method)
return self._get_id() == other._get_id()
File "/model/base.py", line 274, in _get_id # Still in
the same class
return self.id
File
"/lib/python2.6/site-packages/SQLAlchemy-0.7.4-py2.6-linux-x86_64.egg/sqlalchemy/orm/attributes.py",
line 168, in __get__
return self.impl.get(instance_state(instance),dict_)
AttributeError: 'User' object has no attribute '_sa_instance_state'
Thanks
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