On Jan 15, 2012, at 7:46 AM, gpitel wrote:
> I am trying to setup my model initialization in two different ways.
> 1.) Initialize normally by creating an instance, e.g.,
> test0=Test0('Title')
> 2.) Initialize by query, using an input integer as the primary key,
> e.g., test0=Test(32)
>
> This posses two questions. Is it common practice to put a session
> inside the model? Google Code search seems to say no, but I don't see
> any other option. When I query inside the model, the attributes show
> up inside the class but not outside of it. How do I fix this? I have
> included some example code and output.
>
The Session should be created externally to model objects. The Session
represents the *usage* of a series of models, it's not a part of the model
itself. A model object can refer to a session, including it's own session,
but the scope of that session should not be defined by the model object.
In your code example, you'd construct Session right before you say "test0a =
Test0()". Usually, you'd do whatever queries you want here, then call add()
or merge() as needed, outside of the model object itself.
Here, it appears that you're attempting to create a "singleton" object out of
Test0, that is, if someone says Test(2) and id #2 already exists, the
constructor for Test() comes up with that identity as pulled from the Session.
A recipe which illustrates this pattern is at
http://www.sqlalchemy.org/trac/wiki/UsageRecipes/UniqueObject .
> Thanks for your help.
>
> ~Grant
>
> == CODE ==
>
> class Test0(Base):
> __tablename__ = 'test0'
> id = Column(Integer, primary_key=True)
> title = Column(String)
> session=Session()
> def __init__(self, *args):
> if type(args[0])==int:
> test=self.session.query(Test0).get(args[0])
> self=self.session.merge(test)
> self.session.add(self)
> elif type(args[0])==str:
> self.title=args[0]
> self.session.add(self)
> def commit(self):
> self.session.commit()
>
>
> test0a=Test0('This is a test.')
> test0a.commit()
> test0b=Test0(test0a.id)
> print 'test0a title=' + str(test0a.title)
> print 'test0b title=' + str(test0b.title)
> test0b.title='CHANGED'
> test0b.commit()
>
> == OUTPUT ==
> test0a title=This is a test.
> test0b title=None=
>
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