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# scoping.py
# Copyright (C) the SQLAlchemy authors and contributors
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
import sqlalchemy.exceptions as sa_exc
from sqlalchemy.util import ScopedRegistry, to_list, get_cls_kwargs
from sqlalchemy.orm import MapperExtension, EXT_CONTINUE, object_session, \
class_mapper
from sqlalchemy.orm.session import Session
__all__ = ['ScopedSession']
class ScopedSession(object):
"""Provides thread-local management of Sessions.
Usage::
Session = scoped_session(sessionmaker(autoflush=True))
To map classes so that new instances are saved in the current
Session automatically, as well as to provide session-aware
class attributes such as "query":
mapper = Session.mapper
mapper(Class, table, ...)
"""
def __init__(self, session_factory, scopefunc=None):
self.session_factory = session_factory
self.registry = ScopedRegistry(session_factory, scopefunc)
self.extension = _ScopedExt(self)
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):
if self.registry.has():
self.registry().close()
self.registry.clear()
def mapper(self, *args, **kwargs):
"""return a mapper() function which associates this ScopedSession with the Mapper."""
from sqlalchemy.orm import mapper
extension_args = dict((arg, kwargs.pop(arg))
for arg in get_cls_kwargs(_ScopedExt)
if arg in kwargs)
kwargs['extension'] = extension = to_list(kwargs.get('extension', []))
if extension_args:
extension.append(self.extension.configure(**extension_args))
else:
extension.append(self.extension)
return mapper(*args, **kwargs)
def configure(self, **kwargs):
"""reconfigure the sessionmaker used by this ScopedSession."""
self.session_factory.configure(**kwargs)
def query_property(self):
"""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()
"""
class query(object):
def __get__(s, instance, owner):
mapper = class_mapper(owner, raiseerror=False)
if mapper:
return self.registry().query(mapper)
else:
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'):
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))
class _ScopedExt(MapperExtension):
def __init__(self, context, validate=False, save_on_init=True):
self.context = context
self.validate = validate
self.save_on_init = save_on_init
self.set_kwargs_on_init = None
def validating(self):
return _ScopedExt(self.context, validate=True)
def configure(self, **kwargs):
return _ScopedExt(self.context, **kwargs)
def instrument_class(self, mapper, class_):
class query(object):
def __getattr__(s, key):
return getattr(self.context.registry().query(class_), key)
def __call__(s):
return self.context.registry().query(class_)
def __get__(self, instance, cls):
return self
if not 'query' in class_.__dict__:
class_.query = query()
if self.set_kwargs_on_init is None:
self.set_kwargs_on_init = class_.__init__ is object.__init__
if self.set_kwargs_on_init:
def __init__(self, **kwargs):
pass
class_.__init__ = __init__
def init_instance(self, mapper, class_, oldinit, instance, args, kwargs):
if self.save_on_init:
entity_name = kwargs.pop('_sa_entity_name', None)
session = kwargs.pop('_sa_session', None)
if self.set_kwargs_on_init:
for key, value in kwargs.items():
if self.validate:
if not mapper.get_property(key, resolve_synonyms=False,
raiseerr=False):
raise sa_exc.ArgumentError(
"Invalid __init__ argument: '%s'" % key)
setattr(instance, key, value)
kwargs.clear()
if self.save_on_init:
session = session or self.context.registry()
session._save_without_cascade(instance, entity_name=entity_name)
return EXT_CONTINUE
def init_failed(self, mapper, class_, oldinit, instance, args, kwargs):
sess = object_session(instance)
if sess:
sess.expunge(instance)
return EXT_CONTINUE
def dispose_class(self, mapper, class_):
if hasattr(class_, '__init__') and hasattr(class_.__init__, '_oldinit'):
if class_.__init__._oldinit is not None:
class_.__init__ = class_.__init__._oldinit
else:
delattr(class_, '__init__')
if hasattr(class_, 'query'):
delattr(class_, 'query')
|
