# 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,ThreadLocalRegistry,\
to_list, get_cls_kwargs, deprecated
from sqlalchemy.orm import (
EXT_CONTINUE, MapperExtension, class_mapper, object_session
)
from sqlalchemy.orm import exc
from sqlalchemy.orm.session import Session
__all__ = ['ScopedSession']
class ScopedSession(object):
"""Provides thread-local management of Sessions.
Usage::
Session = scoped_session(sessionmaker(autoflush=True))
... use session normally.
"""
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)
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):
"""Dispose of the current contextual session."""
if self.registry.has():
self.registry().close()
self.registry.clear()
@deprecated("Session.mapper is deprecated. "
"Please see http://www.sqlalchemy.org/trac/wiki/UsageRecipes/SessionAwareMapper "
"for information on how to replicate its behavior.")
def mapper(self, *args, **kwargs):
"""return a mapper() function which associates this ScopedSession with the Mapper.
DEPRECATED.
"""
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, 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))
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 = True
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 and class_.__init__ is object.__init__:
class_.__init__ = self._default__init__(mapper)
def _default__init__(ext, mapper):
def __init__(self, **kwargs):
for key, value in kwargs.iteritems():
if ext.validate:
if not mapper.get_property(key, resolve_synonyms=False,
raiseerr=False):
raise sa_exc.ArgumentError(
"Invalid __init__ argument: '%s'" % key)
setattr(self, key, value)
return __init__
def init_instance(self, mapper, class_, oldinit, instance, args, kwargs):
if self.save_on_init:
session = kwargs.pop('_sa_session', None)
if session is None:
session = self.context.registry()
session._save_without_cascade(instance)
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_, 'query'):
delattr(class_, 'query')
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