On Thursday, 26 May 2011 06:42:55 UTC-7, Michael Bayer wrote: > > > On May 25, 2011, at 10:52 PM, Nathan Wright wrote: > > > Hi all, > > > > I've run into an issue when mapping a deferred column_property that uses > a custom SQL construct. I get a KeyError: 'default' because there is no > compile function for the default dialect, but it seems to me that the > default dialect should never be used. > > > > Here's an extended stack trace of what's going on, the important bit is > lines 78-90: > > http://pastebin.com/0kVf9q9q > > > > And here's the a simplified test case: > > > > class utcnow(expression.FunctionElement): > > type = DateTime() > > > > @compiles(utcnow, 'postgresql') > > def pg_utcnow(element, compiler, **kw): > > return "TIMEZONE('utc', CURRENT_TIMESTAMP)" > > > > mapper(AnyClass, any_table, properties={ > > 'timestamp': column_property(select([utcnow()]), deferred=True) > > }) > > > > Session.query(AnyClass).all() > > > > > > For now I'm just adding a dummy @compiles(utcnow) function for the > default dialect, but I think this could be avoided entirely by changing the > NoSuchColumnError message to not cast key (ie, the select) to a string. > Perhaps the repr could be used instead? > > the __repr__() produces IMHO a less descriptive string in the case of a "no > such column" type of situation: > > sqlalchemy.exc.NoSuchColumnError: "Could not locate column in row for > column '<sqlalchemy.sql.expression._Label object at 0x1124490>'" > > > Being able to see the expression is most meaningful. > > http://www.sqlalchemy.org/trac/ticket/2178 provides a patch, which is an > improvement on the situation. >
Now that I see that use case, I'm in total agreement — seeing the full expression when working with a result proxy is very helpful. I've attached a couple of patches to that issue which avoid compiling the expression for internal exceptions. I wasn't sure which approach to take, so each patch takes a slightly different approach and you can decide if either is suitable :) Thanks, Nathan -- 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.
