Michael Bayer wrote: > using a temporary session is still problematic. because the lazy > loading function needs to know how to create one. in many cases, > thats easy, its just create_session(), but as we know in many other > cases, its not, if the session needs to bind to an engine, or if it > binds to muliple engines, etc. i would like to keep all mapper > functionality completely independent of whether or not you are using > Tables bound to Engines or Sessions bound to Engines; the simplistic > version of this idea would require engine-bound tables. > > im not thrilled about the alternatives, which would be a). lazy load > functions that have to reference the engines used to create the > session in the first place (increases latency, memory usage, impacts > pickle-ness of objects, makes great big assumptions about > create_session()), and b). it only works if the Mapper has a > contexual session, which means it doenst work in all cases, and adds > the latency of locating all lazy loaded objects and their children so > that they can be surgically removed from the contexual session after > they are loaded. > > in any case it seems like it forces SA to use some real guesswork/ > assumption making/works-but-then-mysteriously-breaks-in-certain- > configs to make this happen, whereas the hibernate restriction of, > "you have to put your object back into a session somewhere for your > lazy loaders to work again" is absolutely clear. >
That makes sense. I agree, the Hibernate way is probably the right way to go (I knew there was a good reason for it, just never thought it through completely). Now I definitely see that the pre-0.2 behavior was not correct and lazy collections really should fail if the object has been disconnected from its session. Would you agree that SA should raise a clearly identifiable exception when trying to load a lazy relationship on a disconnected object? That would at least make it easy to know what went wrong when it happens. > is it so hard to just stick those objects into some auxilliary session ? No. After my last post I was actually thinking that's the way I would do it anyway. But it's definitely going to cause frustration for newcomers in the ORM scene (it's one of those things you just need to get used to). ~ Daniel _______________________________________________ Sqlalchemy-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users
