Python

Agile Technologies and SQLAlchemy Christopher Perkins PyWorks 2008

What is Agile?

Adaptive

http://www.flickr.com/photos/roblee/442358096/

Collaborative

http://www.flickr.com/photos/gaetanlee/159591865/

Testing

http://www.flickr.com/photos/alisdair/135306281/

What does Python offer?

Virtualenv

http://www.flickr.com/photos/trommetter/128400664/

Paster

http://www.flickr.com/photos/eastlothian/419836784/

Portability

http://www.flickr.com/photos/23072179@N00/2271722618/

And Now For Something Completely Different

Courtesy xkcd.com

Thank God for Python…

Testing

Nose

http://www.flickr.com/photos/cobalt/2373422066/

Test Discovery

Coverage

http://www.flickr.com/photos/stian_olsen/2836208345/

Why Test a Database Schema? Because it’s there Base for majority of your application

Where do we start? Myth: Databases cannot be tested. Myth: Testing a database is hard. Myth: Database testing is SLOW.

SQLAlchemy

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Declarative

Example Model

from sqlalchemy import * from sqlalchemy.orm * from sqlalchemy.ext.declarative import declarative_base metadata = MetaData() Base = declarative_base(metadata=metadata) class DBObject(object): def __init__(self, **kw): for item, value in kw.iteritems(): setattr(self, item, value) barber_style_table = Table('barber_style', metadata, Column('style_id', Integer, ForeignKey('styles.id')), Column('barber_id', Integer, ForeignKey('barbers.id')), ) class Barber(Base, DBObject): __tablename__ = 'barbers' id = Column('id', Integer, primary_key=True) name = Column('name', String(50)) styles = relation('Style', secondary=barber_style_table) class Style(Base, DBObject): __tablename__ = 'styles' id = Column('id', Integer, primary_key=True) name = Column('name', String(50)) class Client(Base, DBObject): __tablename__ = 'clients' id = Column('id', Integer, primary_key=True) name = Column('name', String(50)) style_id = Column('style_id', Integer, ForeignKey('styles.id')) style = relation('Style', backref='clients')

Test Environment from sqlalchemy import create_engine from sqlalchemy.orm import sessionmaker from barbershop.model import * database_created = False def setup_database(): global database_created engine = create_engine(os.environ.get('DBURL', 'sqlite://')) metadata.bind = engine if not database_created: metadata.drop_all() metadata.create_all() database_created = True Session = sessionmaker(bind=engine, autoflush=True, autocommit=True) session = Session() return engine, session

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Your Database will Change

SQLAlchemy Migrate

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Version Control

Upgrade

Downgrade

Documentation

Robustness

http://farm3.static.flickr.com/2029/2229405391_a07aa5b5eb.jpg?v=0

Thanks!

Links  Python Tutorials  http://code.google.com/p/pythontutorials/  This Presentation 

http://pythontutorials.googlecode.com/svn/presentations/AgileSA.ppt

 Barbershop Tutorial 

svn checkout http://pythontutorials.googlecode.com/svn/tutorials/barbershop

 Me 

www.percious.com