(SQLAlchemy - ORM) + Twisted = win

pip install alchimia==0.8.1



alchimia lets you use most of the SQLAlchemy-core API with Twisted, it does not allow you to use the ORM.

Getting started

from alchimia import wrap_engine

from sqlalchemy import (
    create_engine, MetaData, Table, Column, Integer, String
from sqlalchemy.schema import CreateTable

from twisted.internet.defer import inlineCallbacks
from twisted.internet.task import react

def main(reactor):
    engine = wrap_engine(reactor, create_engine("sqlite://"))

    metadata = MetaData()
    users = Table("users", metadata,
        Column("id", Integer(), primary_key=True),
        Column("name", String()),

    # Create the table
    yield engine.execute(CreateTable(users))

    # Insert some users
    yield engine.execute(users.insert().values(name="Jeremy Goodwin"))
    yield engine.execute(users.insert().values(name="Natalie Hurley"))
    yield engine.execute(users.insert().values(name="Dan Rydell"))
    yield engine.execute(users.insert().values(name="Casey McCall"))
    yield engine.execute(users.insert().values(name="Dana Whitaker"))

    result = yield engine.execute(users.select(users.c.name.startswith("D")))
    d_users = yield result.fetchall()
    # Print out the users
    for user in d_users:
        print("Username: %s" % user[users.c.name])
    # Queries that return results should be explicitly closed to
    # release the connection

if __name__ == "__main__":
    react(main, [])


The documentation is all on Read the Docs.


There are some limitations to alchimia's ability to expose the SQLAlchemy API.

  • Some methods simply haven't been implemented yet. If you file a bug, we'll implement them! See CONTRIBUTING.rst for more info.
  • Some methods in SQLAlchemy either have no return value, or don't have a return value we can control. Since most of the alchimia API is predicated on returning Deferred instances which fire with the underlying SQLAlchemy instances, it is impossible for us to wrap these methods in a useful way. Luckily, many of these methods have alternate spelling. The docs call these out in more detail.