Session = sessionmaker(bind=engine)
work_session = Session()
### Ensure an empty database (so you can run this script more than once)
for cls in (Student, Course):
for obj in work_session.query(cls).all():
work_session.delete(obj)
### Build non-empty initial state
fred = Student(id=1, name="Fred Brooks")
diana = Student(id=4, name="Diana Shirley")
phy = Course(id=2, title="Phy 101")
cs = Course(id=3, title="CS Basics")
fred.courses = [cs]
diana.courses = [phy]
for it in (fred, diana, phy, cs):
work_session.merge(it)
work_session.commit()
show(work_session, "init state")
### Open up a second session on the same engine
read_session = Session()
### Make some changes in the work_session
elaine = Student(id=5, name="Elanor Rigby")
math = Course(id=4, title="Calc 7", students=[fred, diana, elaine])
