On Sun, Mar 6, 2011 at 5:21 PM, Michael Bayer <mike...@zzzcomputing.com>wrote:
> > On Mar 6, 2011, at 8:16 PM, Lenza McElrath wrote: > > Ok cool. I actually could write my code to produce exactly that effect > fairly quickly since I was already accessing the mutable object through a > comparable_property on the model. It was surprising how easy it was > actually... SQLAlchemy really makes things awesome. > > We will start looking at moving to SQLAlchemy 0.7. It will probably be > hard to convince people to move to a "beta" version on production systems > though. When do you expect 0.7 to leave beta? > > I wonder if you could help with one other issue I have occationally > observed that might be related to this. Sometimes of these mutable objects > are None (myobject.value == None). These values are non-nullable columns > in the database, and should always be represented as an actual class in > logic. I have suspected this issue is related to objects being expired (by > explicitly called session.expire()) and then detached from the session. But > it seemed like SQLAlchemy should always either return a correct value or > raise an exception. Returning None could result in incorrect behavor for > code that does: if myobject.value: save_the_world(). Does it make sense > that this would be happening? I think I saw documentation explaining that > attribute values are loaded individually once they are expired? Could the > resurrecting of state not be happening properly when only loading a single > attribute? > > > expired attributes don't return None - they invoke a SELECT from the > database when they are accessed, or raise an error (to the chagrin of many > users) if the object is not associated with a session. > > I don't know offhand what would make your values come back as None, > wondering what you mean by "resurrecting", are you pickling the parent > objects as well ? Without looking at the source I suppose that would be > somewhat suspect though pickling/unpickling of mapped objects is well tested > and supported. > No pickling is happening. By "resurrect" I mean whatever is happening in MutableAttrInstanceState.__resurrect. I am definitely getting a None and not an error -- I happen to have an "assert myobject.value is not None". I will try to make a test case. It is hard because I don't know exactly how to trigger this code path. I ran into an issues here before with mutable columns not being updated after resurrecting (fixed in r26f423a667ca). If I recall the test case I made for that it involved modifying the attribute in one function and then flushing the session in another. -- 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.
