Michael Bayer wrote: > On Jun 25, 2008, at 10:48 AM, Huy Do wrote: > > >> Hi, >> >> I read in the 0.5 release notes that the c attribute was no longer >> necessary when doing queries using the mapped class, but I did not see >> it mentioned that the c attribute was removed all together. >> >> It's just that I've been using the c attribute in my Mapped classes to >> access the database/table metadata and now all my code will need to be >> changed to use the table.c attribute instead. >> >> Was there a reason for removing the c attribute from mapped classes >> altogether ? >> >> > > in 0.5, the attributes on classes vs. the columns on Tables are very > different beasts now. Its not at all the same thing if you say: > > sess.query(MyClass.id, MyClass.name) > > vs. > > sess.query(mytable.c.id, mytable.c.name) > > > since in the former case, we know that we are dealing with the MyClass > mapper; in the latter case, we're not. The behavior of things like > join(), polymorphic loading, other options, etc. are completely > different - in the case of joined table inheritance it's dramatically > different, where "Subclass.id" and "subtable.c.id" are literally > different columns. So we really can't have a casual ".c." attribute > hanging around on classes with the new behavior; the user needs to be > very explicit when choosing between MyClass.attr vs. table.c.attr. > > That said, you can retroactively add your ".c." attribute using a > MapperExtension that implements "instrument_class()", and assigns the > "c" attribute from the table to the class. > Michael,
Thanks for the suggestion. Is there any metadata on the MyClass.id field at all ? like which column it's mapped too ? Lucky for me, I don't use any of the advanced SA features like inheritance and polymorphic stuff, so usually my MyClass.id is the same as my mytable.c.id (in the old SA). Thanks again, Huy --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
