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205
sqlalchemy/orm/scoping.py
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205
sqlalchemy/orm/scoping.py
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# scoping.py
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# Copyright (C) the SQLAlchemy authors and contributors
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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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import sqlalchemy.exceptions as sa_exc
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from sqlalchemy.util import ScopedRegistry, ThreadLocalRegistry, \
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to_list, get_cls_kwargs, deprecated
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from sqlalchemy.orm import (
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EXT_CONTINUE, MapperExtension, class_mapper, object_session
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)
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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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Usage::
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Session = scoped_session(sessionmaker(autoflush=True))
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... use session normally.
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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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self.extension = _ScopedExt(self)
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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("Scoped session is already present; 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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@deprecated("Session.mapper is deprecated. "
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"Please see http://www.sqlalchemy.org/trac/wiki/UsageRecipes/SessionAwareMapper "
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"for information on how to replicate its behavior.")
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def mapper(self, *args, **kwargs):
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"""return a mapper() function which associates this ScopedSession with the Mapper.
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DEPRECATED.
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"""
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from sqlalchemy.orm import mapper
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extension_args = dict((arg, kwargs.pop(arg))
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for arg in get_cls_kwargs(_ScopedExt)
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if arg in kwargs)
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kwargs['extension'] = extension = to_list(kwargs.get('extension', []))
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if extension_args:
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extension.append(self.extension.configure(**extension_args))
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else:
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extension.append(self.extension)
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return mapper(*args, **kwargs)
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def configure(self, **kwargs):
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"""reconfigure the sessionmaker used by this ScopedSession."""
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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 against the
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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', 'is_active', '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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class _ScopedExt(MapperExtension):
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def __init__(self, context, validate=False, save_on_init=True):
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self.context = context
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self.validate = validate
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self.save_on_init = save_on_init
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self.set_kwargs_on_init = True
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def validating(self):
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return _ScopedExt(self.context, validate=True)
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def configure(self, **kwargs):
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return _ScopedExt(self.context, **kwargs)
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def instrument_class(self, mapper, class_):
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class query(object):
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def __getattr__(s, key):
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return getattr(self.context.registry().query(class_), key)
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def __call__(s):
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return self.context.registry().query(class_)
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def __get__(self, instance, cls):
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return self
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if not 'query' in class_.__dict__:
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class_.query = query()
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if self.set_kwargs_on_init and class_.__init__ is object.__init__:
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class_.__init__ = self._default__init__(mapper)
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def _default__init__(ext, mapper):
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def __init__(self, **kwargs):
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for key, value in kwargs.iteritems():
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if ext.validate:
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if not mapper.get_property(key, resolve_synonyms=False,
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raiseerr=False):
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raise sa_exc.ArgumentError(
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"Invalid __init__ argument: '%s'" % key)
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setattr(self, key, value)
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return __init__
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def init_instance(self, mapper, class_, oldinit, instance, args, kwargs):
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if self.save_on_init:
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session = kwargs.pop('_sa_session', None)
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if session is None:
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session = self.context.registry()
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session._save_without_cascade(instance)
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return EXT_CONTINUE
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def init_failed(self, mapper, class_, oldinit, instance, args, kwargs):
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sess = object_session(instance)
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if sess:
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sess.expunge(instance)
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return EXT_CONTINUE
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def dispose_class(self, mapper, class_):
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if hasattr(class_, 'query'):
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delattr(class_, 'query')
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