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# orm/scoping.py
# Copyright (C) 2005-2011 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
from sqlalchemy import exc as sa_exc
from sqlalchemy.util import ScopedRegistry, ThreadLocalRegistry, warn
from sqlalchemy.orm import class_mapper
from sqlalchemy.orm import exc as orm_exc
from sqlalchemy.orm.session import Session
__all__ = ['ScopedSession']
class ScopedSession(object):
"""Provides thread-local management of Sessions.
Usage::
Session = scoped_session(sessionmaker())
... use Session normally.
The internal registry is accessible as well,
and by default is an instance of :class:`.ThreadLocalRegistry`.
"""
def __init__(self, session_factory, scopefunc=None):
self.session_factory = session_factory
if scopefunc:
self.registry = ScopedRegistry(session_factory, scopefunc)
else:
self.registry = ThreadLocalRegistry(session_factory)
def __call__(self, **kwargs):
if kwargs:
scope = kwargs.pop('scope', False)
if scope is not None:
if self.registry.has():
raise sa_exc.InvalidRequestError("Scoped session is already present; "
"no new arguments may be specified.")
else:
sess = self.session_factory(**kwargs)
self.registry.set(sess)
return sess
else:
return self.session_factory(**kwargs)
else:
return self.registry()
def remove(self):
"""Dispose of the current contextual session."""
if self.registry.has():
self.registry().close()
self.registry.clear()
def configure(self, **kwargs):
"""reconfigure the sessionmaker used by this ScopedSession."""
if self.registry.has():
warn('At least one scoped session is already present. '
' configure() can not affect sessions that have '
'already been created.')
self.session_factory.configure(**kwargs)
def query_property(self, query_cls=None):
"""return a class property which produces a `Query` object against the
class when called.
e.g.::
Session = scoped_session(sessionmaker())
class MyClass(object):
query = Session.query_property()
# after mappers are defined
result = MyClass.query.filter(MyClass.name=='foo').all()
Produces instances of the session's configured query class by
default. To override and use a custom implementation, provide
a ``query_cls`` callable. The callable will be invoked with
the class's mapper as a positional argument and a session
keyword argument.
There is no limit to the number of query properties placed on
a class.
"""
class query(object):
def __get__(s, instance, owner):
try:
mapper = class_mapper(owner)
if mapper:
if query_cls:
# custom query class
return query_cls(mapper, session=self.registry())
else:
# session's configured query class
return self.registry().query(mapper)
except orm_exc.UnmappedClassError:
return None
return query()
def instrument(name):
def do(self, *args, **kwargs):
return getattr(self.registry(), name)(*args, **kwargs)
return do
for meth in Session.public_methods:
setattr(ScopedSession, meth, instrument(meth))
def makeprop(name):
def set(self, attr):
setattr(self.registry(), name, attr)
def get(self):
return getattr(self.registry(), name)
return property(get, set)
for prop in ('bind', 'dirty', 'deleted', 'new', 'identity_map', 'is_active', 'autoflush'):
setattr(ScopedSession, prop, makeprop(prop))
def clslevel(name):
def do(cls, *args, **kwargs):
return getattr(Session, name)(*args, **kwargs)
return classmethod(do)
for prop in ('close_all', 'object_session', 'identity_key'):
setattr(ScopedSession, prop, clslevel(prop))
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