refresh doesn't remove any objects from the session so its a matter of what is present in the session, not marked as dirty, and strongly referenced on the outside. if you're using refresh you shouldn't care about how it gets data back into the collection.
Kent wrote: > What's strange is that I can't recreate the problem on more simple > stage. Every time I refresh() on the parent object, the list objects > remain the same. In other words, *sometimes* it behaves as I hope it > to (by apparently refreshing the list's objects) and *sometimes* if > throws them out and creates new ones. The mystery to me is what > determines when it will create new instances vs. refreshing the > existing ones? > > > > On Mar 4, 3:24 pm, "Michael Bayer" <mike...@zzzcomputing.com> wrote: >> Kent wrote: >> > If I use session.refresh(obj) to re-load an obj that has a one-to-many >> > relational property, the objects in the list are *replaced* instead of >> > *refreshed* if they already exist. >> >> > Suppose department has a list of employees: >> >> > suppose dept.employees = [ emp1, emp2 ] >> >> > session.refresh(dept) >> >> > the dept."employees" list's elements are replaced with new objects >> > instead of reusing those that existed and refreshing them. >> >> > Is it possible to have those same objects re-used and simply refreshed >> > instead of replaced? >> >> you can only turn off "refresh-expire" cascade, which will prohibit the >> operation from traveling into the child objects. the collection is >> still >> refreshed for obvious reasons, its one of the attributes on your mapped >> object. >> >> To achieve your specified behavior, use session.refresh() given as its >> second argument the set of attribute names which are safe to be reloaded >> completely (in this case the scalars). Then for each uselist >> attribute, >> iterate the collection of each and call the desired version of >> session.refresh() for those. >> >> This is an easy refresh() function to create in a generalized way by >> inspecting the class-level attributes of the incoming object. >> >> >> >> > -- >> > You received this message because you are subscribed to the Google >> Groups >> > "sqlalchemy" group. >> > To post to this group, send email to sqlalch...@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 sqlalch...@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 sqlalch...@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.
