On Mon, Oct 26, 2009 at 9:13 AM, Joril <jor...@gmail.com> wrote: > > On 26 Ott, 13:41, Mike Conley <mconl...@gmail.com> wrote: > > > I see, but I need a proper shallow copy instead, with every > > > attribute.. Is there no way? :/ > > > > > What is missed? > > > > I am not sure what you mean by shallow copy. The fact that there are > > relations to be lazy loaded is present in the new object when > instantiated. > > Obviously the objects pointed to by the relation are not copied, but I > would > > call that a deep copy, and to do that you would need to iterate over them > > also. > > I'm sorry, by "shallow copy" I mean that only the parent object should > be a copy (=different instance), while the related ones should be kept > as-is... > > For example, given an object A that references B and C, a shallow copy > of A would be made up of a copy of A that references the original B > and C (not copies of B or C). > > So, in Python a non-automatic shallow copy would be: > > A = Some_class() > A.refs = [B, C] > Acopy = Some_class() > Acopy.refs = A.refs > > My problem is that if A.refs has to be lazy loaded, when I try to copy > it over to Acopy, it triggers the query, and I'd like to avoid that, > while still copying the fact that Acopy.refs should be the same as > A.refs. > > Thanks for your attention again! > > So, let's understand the underlying data model.
We say, A is a parent object related to B and C children. (1) If this is a one-to-many relationship, then B and C will contain foreign keys pointing at A. Copying of A to Acopy cannot have references point at [B, C] because the children cannot point at two parents at the same time; there is only one foreign key column. (2) If this is a many-to-many relationship, then there will be another table between A and [B,C] managing the many-to-many connection and something needs to be done during the copy to preserve the relationships. Which do we have here? --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
