iky/nameko-sqlalchemy

SQLAlchemy dependency for nameko services

nameko-sqlalchemy

A SQLAlchemy dependency for nameko, enabling services to interface with a relational database.

Usage

from nameko_sqlalchemy import Session

from .models import Model, DeclarativeBase

class Service(object):

    session = Session(DeclarativeBase)

    @entrypoint
    def write_to_db(self):
        model = Model(...)
        self.session.add(model)
        self.session.commit()

    @entrypoint
    def query_db(self):
        queryset = self.session.query(Model).filter(...)
        ...

Database drivers

You may use any database driver compatible with SQLAlchemy provided it is safe to use with eventlet. This will include all pure-python drivers. Known safe drivers are:

• pysqlite (tested in this repo)
• pymysql

Pytest fixtures

Pytest fixtures to allow for easy testing are available.

• db_session fixture (which depends on db_connection fixture) will instantiate test database and tear it down at the end of each test.
• model_base fixture can be overridden to provide custom declarative_base.
• db_engine_options fixture can be overriden to provide additional keyword arguments to sqlalchemy.create_engine.

import pytest

from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base


class Base(object):
    pass


DeclarativeBase = declarative_base(cls=Base)


class User(DeclarativeBase):
    __tablename__ = "users"

    id = Column(Integer, primary_key=True)
    name = Column(String)


@pytest.fixture(scope='session')
def model_base():
    return DeclarativeBase


@pytest.fixture(scope='session')
def db_engine_options():
    return dict(client_encoding='utf8')


def test_users(db_session):
    user = User(id=1, name='Joe')
    db_session.add(user)
    db_session.commit()
    saved_user = db_session.query(User).get(user.id)
    assert saved_user.id > 0
    assert saved_user.name == 'Joe'

When running tests you can pass database test url with --test-db-url parameter or override db_url fixture. By default SQLite memory database will be used.

py.test test --test-db-url=sqlite:///test_db.sql