On Jun 25, 10:50 am, Michael Bayer <[EMAIL PROTECTED]> wrote: > On Jun 25, 2008, at 1:24 PM, bukzor wrote: > > > > > Thanks for that versioning overview. > > > Sorry for changing the topic (Should I make a separate post?), but is > > there a way to make the joins more automatic? > > > I'd like to just specify some filter against table A and another > > against table B and have the system join them, even if the join needs > > to go through C or D. Of course the results would be undefined if > > there was more than one path between A and B, but this is not the case > > in my database and I'm sure a good subset of most databases. Will I > > need to roll this myself? Would people appreciate it if I added this > > functionality to the mapper class? If so, what code would you suggest > > editing? I just need some representation of the database as a graph. > > While you're of course free to create your own Query subclass which > implements a graph traversal of relations to achieve this effect, this > actual functionality was long ago removed (in the form of the old > "join_by()" method), since it amounts to guessing; issues were > apparent almost immedately after its introduction and it was soon > deprecated. It requires an expensive graph traversal each time it's > used, and leads to applications that silently, randomly fail as soon > as a new foreign key path between the two target tables is added. It > fits perfectly the kind of behavior that's targeted by "explicit is > better than implicit".
Sorry for being a pest, but I've looked at the documentation and really can't figure this out. If a mapped class is a node of our graph, where do I find the edges, and how do I get to the next node. Alternatively, should I do this at the table/sql level rather than the class/orm level? How did you yourself learn this? Is there some other reference I'm overlooking? --Buck --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
