21. Pattern¶

Overview¶

There are some common pattern that I often use when working with sqlalchemy since then.

Patterns¶

Using context manager with session¶

I usually have this kind of pattern when working with sqlalchemy:

session = get_the_session_one_way_or_another()

try: # do something with the session except: # * see comment below session.rollback() raise else: session.commit()

To make things easier to use, it is useful to have this as a context manager:

@contextmanager
def get_session():
    session = get_the_session_one_way_or_another()

    try:
        yield session
    except:
        session.rollback()
        raise
    else:
        session.commit()

This code snippset when I build ASGI application with focus on CRUD on databases tasks (insert, update, delete)

And then:

with get_session() as session: # do something with the session

https://stackoverflow.com/questions/52232979/sqlalchemy-rollback-when-exception