So if I read the documentation right, it appears that because I'm accessing the object via the primary key, it looks the object up locally (i.e. in the session) and returns that object. Other than doing a query/lookup on another attribute, how can I force it to create the object from the data in the database?
The key here is that I'd like to be able to verify if an attribute (that corresponds to a DB column) has been deleted. To complicate matters, I'd also like to be able to do this in a nested transaction, without destroying the session (so I can rollback everything when I'm done). Thanks, Mike On Oct 14, 7:00 am, "Michael Bayer" <mike...@zzzcomputing.com> wrote: > mviamari wrote: > > > Hello, > > > I'm writing tests for my database, and I've run into a little bit of > > confusion. > > > Say I have a class (we'll call it person) with two declared attributes > > that correspond to db columns: > > > person.id > > person.name > > > If I randomly assign a person object another attribute dynamically: > > > person.undeclared_value = 'New' > > > That value doesn't get stored in the database. (That part I expected > > and understand). > > What I don't understand is if I commit the object, set it to None (to > > presumably garbage collect it) and then reacquire it from the DB, > > sometimes that dynamically declared attribute is still pesent: > > > person = Person() > > person.name = 'John Smith' > > person.new_attr = 'New' > > > commit() > > id = person.id #id isn't assigned till after a commit > > > person = None > > person = Person.get_by(id=id) > > > #This is expected to be true > > assert person.name = 'John Smith' > > > #This is expected to yield an AttributeError, but sometimes it doesn't > > assert person.new_attr = 'New' > > > Based on my tests, it appears that the sometimes it doesn't is > > whenever there are relationships created in the session. If I only > > create one object and follow the above pattern, I get the expected > > results. If I create two objects and the relationship between them, > > then I get the unexpected results. > > > Does anyone have any idea what might be going on? I think the object > > is getting stored in the session, and when I reobtain the object it > > just uses the reference in the session. > > this is the identity map at work. Read "Is the session a cache?" > athttp://www.sqlalchemy.org/docs/05/session.html#frequently-asked-quest... > . --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
