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. > > On Fri, Mar 4, 2011 at 2:16 PM, Michael Bayer <mike...@zzzcomputing.com> > wrote: > > On Mar 4, 2011, at 5:09 PM, Lenza McElrath wrote: > > > > > So there is no way to accomplish this in 0.6? I was looking at doing it > > the way I describe above, but it is not trivial to figure out which > > model/session a value is attached to. And I guess it is theoretically > > possible that a value could be connected to two models/sessions. > > Definitely scared of moving to an untested code... but looks like there are > > lots of improvements in 0.7 that might make it worth it... > > well, the on-change event required some less than trivial features so its an > 0.7 thing. The best solution of all is to not use mutable types in the first > place. I.e. if you need to change a scalar value in place, do something > like myobject.value = value.mutate(xyz). > > > > > > > > > > > -- > > 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. > > -- > 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. > > > > -- > 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. -- 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.
