from sqlalchemy import engine_from_config
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from sqlalchemy.orm import sessionmaker
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from sqlalchemy.orm import configure_mappers
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import zope.sqlalchemy
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# import or define all models here to ensure they are attached to the
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# Base.metadata prior to any initialization routines
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from .mymodel import MyModel # flake8: noqa
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# run configure_mappers after defining all of the models to ensure
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# all relationships can be setup
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configure_mappers()
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def get_engine(settings, prefix='sqlalchemy.'):
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return engine_from_config(settings, prefix)
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def get_session_factory(engine):
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factory = sessionmaker()
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factory.configure(bind=engine)
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return factory
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def get_tm_session(session_factory, transaction_manager):
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"""
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Get a ``sqlalchemy.orm.Session`` instance backed by a transaction.
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This function will hook the session to the transaction manager which
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will take care of committing any changes.
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- When using pyramid_tm it will automatically be committed or aborted
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depending on whether an exception is raised.
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- When using scripts you should wrap the session in a manager yourself.
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For example::
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import transaction
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engine = get_engine(settings)
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session_factory = get_session_factory(engine)
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with transaction.manager:
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dbsession = get_tm_session(session_factory, transaction.manager)
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"""
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dbsession = session_factory()
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zope.sqlalchemy.register(
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dbsession, transaction_manager=transaction_manager)
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return dbsession
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def includeme(config):
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"""
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Initialize the model for a Pyramid app.
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Activate this setup using ``config.include('tutorial.models')``.
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"""
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settings = config.get_settings()
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settings['tm.manager_hook'] = 'pyramid_tm.explicit_manager'
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# use pyramid_tm to hook the transaction lifecycle to the request
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config.include('pyramid_tm')
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# use pyramid_retry to retry a request when transient exceptions occur
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config.include('pyramid_retry')
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session_factory = get_session_factory(get_engine(settings))
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config.registry['dbsession_factory'] = session_factory
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# make request.dbsession available for use in Pyramid
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config.add_request_method(
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# r.tm is the transaction manager used by pyramid_tm
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lambda r: get_tm_session(session_factory, r.tm),
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'dbsession',
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reify=True
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)
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