On May 24, 3:44 pm, Larry Martell <larry.mart...@gmail.com> wrote: > On Thu, May 24, 2012 at 2:27 AM, bruno desthuilliers > > <bruno.desthuilli...@gmail.com> wrote: > > On May 23, 10:39 pm, Larry Martell <larry.mart...@gmail.com> wrote: > >> I was asked to make a mod to a large django app that I didn't write. > >> They wanted me to add a derived field to a query, e.g. select > >> col1-col2 from table ... > > > I assume you're talking about using queryset.extra ? > > No I build the query myself.
Are you using the ORM at all ? > >> I did that and it works, but in some other part of the code it calls > >> getattr(object, field) and when field == col1-col2 it blows up > >> with"object has no attribute 'col1-col2'" > > > Are you sure the instance on which it failed was retrieved using the > > appropriate query ? > > That could be the case. What happens is the data set returned creates > a chart. The points on the chart are clickable links that drill down > and generate a more detailed chart. It's in that secondary chart that > the error occurs. But OTOH, getattr does retrieve the attributes of > the actual columns from the initial query, so it much be the same > instance. Except that, very obviously, it isn't. > > Can you post the relevant parts of your code ? (here or via dpaste ?) > > Unfortunately, no. It's a lot of code with a ton of inherited classes. Uhu. Real life vs example code, as usual. So all you can do is trace your code using the logging module (or print statements) and the debugger. -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
