from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker


class DB(object):
    def __init__(self, address, debug=False):
        self.engine = engine = create_engine(address, echo=debug)
        self.sessionmaker = sessionmaker(engine)

    def __enter__(self):
        self.session = session = self.sessionmaker()
        return session

    def __exit__(self, exc_type, exc_value, traceback):
        session = self.session
        try:
            if exc_type is None and session.is_active:
                session.commit()
        finally:
            session.close()