SQLAlchemy: Creating vs. Reusing a Session

Question

Just a quick question: SQLAlchemy talks about calling sessionmaker() once but calling the resulting Session() class each time you need to talk to y

Answer 1

In addition to the excellent zzzeek's answer, here's a simple recipe to quickly create throwaway, self-enclosed sessions:

from contextlib import contextmanager

from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker

@contextmanager
def db_session(db_url):
    """ Creates a context with an open SQLAlchemy session.
    """
    engine = create_engine(db_url, convert_unicode=True)
    connection = engine.connect()
    db_session = scoped_session(sessionmaker(autocommit=False, autoflush=True, bind=engine))
    yield db_session
    db_session.close()
    connection.close()

Usage:

from mymodels import Foo

with db_session("sqlite://") as db:
    foos = db.query(Foo).all()