# Copyright (c) 2012 netzguerilla.net <iro@netzguerilla.net>

# 

# This file is part of Iro.

# 

# Permission is hereby granted, free of charge, to any person obtaining a copy of

# this software and associated documentation files (the "Software"), to deal in

# the Software without restriction, including without limitation the rights to use,

# copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the

# #Software, and to permit persons to whom the Software is furnished to do so,

# subject to the following conditions:

# 

# The above copyright notice and this permission notice shall be included in

# all copies or substantial portions of the Software.

# 

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,

# INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A

# PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT

# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION

# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

from sqlalchemy.orm import sessionmaker

class WithSession(object):

    '''a with statement for a database session connection.'''

    def __init__(self, engine, autocommit=False):

        """

        :param `sqlalchemy.engine.base.Engine` engine: a valid sqlalchemy engine object (normally created via :func:`sqlalchemy.create_engine`).

        :param boolean autocommit: autocommit after running the function.

        .. automethod:: __enter__

        .. automethod:: __exit__

        """

        self.engine = engine

        self.autocommit=autocommit

    def __enter__(self):

        """returns a vaild session object."""

        self.session = sessionmaker(bind=self.engine)()

        return self.session

    def __exit__(self,exc_type, exc_value, traceback):

        if exc_type is None:

            if self.autocommit:

                self.session.commit()

        else:

            self.session.rollback()

        self.session.close()