On Jan 14, 11:05 pm, Michael Bayer <mike...@zzzcomputing.com> wrote:
> On Jan 14, 2009, at 12:58 PM, koranthala wrote:
>
>
>
> > Hi,
> > I moved my application from 0.4 to 0.5 and now I am finding that it
> > is not working - the error is ->
> > sqlalchemy.exc.UnboundExecutionError: Instance <Data at 0x1357110> is
> > not bound to a Session; attribute refresh operation cannot proceed
>
> > I read through other mail chains and it looks like removal of
> > get_session() method on Mapper is the reason for this.
> > I actually take objects from one session to pass it to other
> > threads where the data is modified and saved. So, I cannot keep the
> > session open across threads (at least not without introducing kludgy
> > code).
>
> > Is there any way of handling this - should I go back to 0.4?
>
> get_session() created implicit behavior of placing an object in a
> session when none was available, so your application could be
> surprised to find an object bound to a certain session, which could
> later cause thread-unsafe access if the object were moved to yet
> another thread but not removed from the previous session. so take
> your existing logic which removes the object from one session and
> passes to a new thread to also add() (or merge()) the object to the
> session corresponding to that thread. your code will be better off
> for its explicitness in this area.
I understood your point and tried updating my code as mentioned.
My code is a medium complex one - ~2K lines
A problem that I see is that since I take the object and use it at
many (~20) places, every single place I have to have a code like -
m = session.merge(o)
self.data[i] = m
which is added.
This seems very broilerplate - and there is no easy way to avoid it -
without writing a get_session myself - or having a separate object for
it.
How is it handled in other projects?
I would be very thankful if someone can help me out here.
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