Hi All,
I'm looking for examples of MapperExtensions.
Specifically, I'm looking to implement one that creates new rows when
certain attributes of an object changes.
I'm not sure if this is the right approach, so here's some pseudocode of
how I'd like to use the end result:
class MyThing(Base,Versioned):
__tablename__ = 'whatever'
id = Column(Integer, primary_key=True)
name = Column(String(80))
value = Column(Numeric(precision=36, scale=12))
__versioned__ = ('value',)
valid_from = Column(DateTime())
valid_to = Column(DateTime())
>>> x = MyThing(name='foo',value=100)
>>> x.id
None
>>> session.add(x)
>>> session.commit()
>>> x.id, x.name, x.value, x.valid_from, x.valid_to
1, 'foo', 100, 2010-06-29 09:00, None
>>> x.value = 200
>>> session.commit()
>>> x.id, x.name, x.value, x.valid_from, x.valid_to
2, 'foo', 200, 2010-06-29 09:05, None
>>> for thing in session.query(MyThing).all():
... print x.id, x.name, x.value, x.valid_from, x.valid_to
1, 'foo', 100, 2010-06-29 09:00, 2010-06-29 09:05
2, 'foo', 200, 2010-06-29 09:05, None
Is a MapperExtension the right way to go here?
If so, what's the correct method to change the primary key of x in?
cheers,
Chris
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