On Jun 29, 2011, at 3:22 PM, Torsten Landschoff wrote: > Hi Michael, hi *, > > here is another issue I ran into with SQLAlchemy. Basically, I am trying > to map a filesystem like structure to SQL. Unfortunately, there is a > difference in that the users can reorder the tree. I reduced my code to > the attached example. > > Mapping the structure worked quite good so far, until I noticed that I > had duplicate entries in the same folder. So I added a unique constraint > with the result that I can't overwrite the list of entries anymore: > > folder.children = list(folder.children) > > alone causes the problem. SQLAlchemy adds the 'new' entries first, which > violates the unique constraint.
yeah ordering_list can't handle this use case. It doesn't know how to "reverse" the order of two keys where a unique exists between them, that would imply it would know how to temporarily update the row to a third neutral value - only the flush procedure could allow an operation like this which is outside the scope of the ordering list itself. > > Is there a way to do what I want without bigger changes to the code? For > now, I will disable the unique constraint again and add some checks to > the Python code. > > Greetings, Torsten > > -- > DYNAmore Gesellschaft fuer Ingenieurdienstleistungen mbH > Torsten Landschoff > > Office Dresden > Tel: +49-(0)351-4519587 > Fax: +49-(0)351-4519561 > > mailto:torsten.landsch...@dynamore.de > http://www.dynamore.de > > Registration court: Mannheim, HRB: 109659, based in Karlsruhe, > Managing director: Prof. Dr. K. Schweizerhof, Dipl.-Math. U. Franz > > -- > 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. > > <fsdemo.py> -- 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.
