.py

from contextlib import contextmanager

from flask import current_app
from sqlalchemy.orm import sessionmaker

from app.extensions import alchemy


@contextmanager
def session(engine_name):
    Session = sessionmaker(bind=alchemy.get_engine(current_app, engine_name))
    session = Session()
    try:
        yield session
        session.commit()
    except:
        session.rollback()
        raise
    finally:
        session.close()

read_session = lambda: session('read')
write_session = lambda: session('write')