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135 lines
4.5 KiB
135 lines
4.5 KiB
# orm/scoping.py
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# Copyright (C) 2005-2012 the SQLAlchemy authors and contributors <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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from sqlalchemy import exc as sa_exc
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from sqlalchemy.util import ScopedRegistry, ThreadLocalRegistry, warn
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from sqlalchemy.orm import class_mapper
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from sqlalchemy.orm import exc as orm_exc
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from sqlalchemy.orm.session import Session
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__all__ = ['ScopedSession']
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class ScopedSession(object):
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"""Provides thread-local management of Sessions.
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Typical invocation is via the :func:`.scoped_session`
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function::
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Session = scoped_session(sessionmaker())
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The internal registry is accessible,
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and by default is an instance of :class:`.ThreadLocalRegistry`.
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See also: :ref:`unitofwork_contextual`.
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"""
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def __init__(self, session_factory, scopefunc=None):
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self.session_factory = session_factory
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if scopefunc:
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self.registry = ScopedRegistry(session_factory, scopefunc)
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else:
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self.registry = ThreadLocalRegistry(session_factory)
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def __call__(self, **kwargs):
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if kwargs:
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scope = kwargs.pop('scope', False)
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if scope is not None:
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if self.registry.has():
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raise sa_exc.InvalidRequestError(
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"Scoped session is already present; "
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"no new arguments may be specified.")
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else:
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sess = self.session_factory(**kwargs)
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self.registry.set(sess)
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return sess
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else:
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return self.session_factory(**kwargs)
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else:
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return self.registry()
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def remove(self):
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"""Dispose of the current contextual session."""
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if self.registry.has():
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self.registry().close()
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self.registry.clear()
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def configure(self, **kwargs):
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"""reconfigure the sessionmaker used by this ScopedSession."""
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if self.registry.has():
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warn('At least one scoped session is already present. '
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' configure() can not affect sessions that have '
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'already been created.')
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self.session_factory.configure(**kwargs)
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def query_property(self, query_cls=None):
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"""return a class property which produces a `Query` object
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against the class when called.
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e.g.::
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Session = scoped_session(sessionmaker())
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class MyClass(object):
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query = Session.query_property()
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# after mappers are defined
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result = MyClass.query.filter(MyClass.name=='foo').all()
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Produces instances of the session's configured query class by
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default. To override and use a custom implementation, provide
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a ``query_cls`` callable. The callable will be invoked with
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the class's mapper as a positional argument and a session
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keyword argument.
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There is no limit to the number of query properties placed on
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a class.
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"""
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class query(object):
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def __get__(s, instance, owner):
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try:
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mapper = class_mapper(owner)
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if mapper:
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if query_cls:
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# custom query class
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return query_cls(mapper, session=self.registry())
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else:
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# session's configured query class
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return self.registry().query(mapper)
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except orm_exc.UnmappedClassError:
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return None
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return query()
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def instrument(name):
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def do(self, *args, **kwargs):
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return getattr(self.registry(), name)(*args, **kwargs)
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return do
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for meth in Session.public_methods:
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setattr(ScopedSession, meth, instrument(meth))
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def makeprop(name):
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def set(self, attr):
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setattr(self.registry(), name, attr)
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def get(self):
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return getattr(self.registry(), name)
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return property(get, set)
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for prop in ('bind', 'dirty', 'deleted', 'new', 'identity_map',
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'is_active', 'autoflush', 'no_autoflush'):
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setattr(ScopedSession, prop, makeprop(prop))
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def clslevel(name):
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def do(cls, *args, **kwargs):
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return getattr(Session, name)(*args, **kwargs)
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return classmethod(do)
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for prop in ('close_all', 'object_session', 'identity_key'):
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setattr(ScopedSession, prop, clslevel(prop))
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