On Mon, Jan 18, 2010 at 5:25 PM, Alex Robbins wrote:
> Hmm, you might also look at just doing something like
> Event.objects.values_list
> ('classes_involved__parent_disciplines__name', flat=True).distinct().
> That works on some relations, but I haven't tested it in your case.
I tried that and a few variations, e.g:
self.get('classes_involved__parent_discipline').values_list('name',
flat=True).distinct()
or
self.classes_involved.parent_discipline.values_list('name',
flat=True).distinct()
But I always get to either an attribute error (e.g. Event has no get)
or an instance error, i.e. I'm working with an instance rather than a
queryset. This seems to be a dead end. Reading around on instance
errors, it seems to be common for methods on models, and the answer
seems to be a manager class, but I'm struggling to work out how to
access related fields from a model instance. Especially ones that are
two deep.
> Second problem: Save doesn't work right.
> You could try doing a super(Event, self).save(*args, **kwargs) before you
> compute the disciplines list, and then again after you have computed
> it, to save the value.
Good idea, but unfortunately doesn't work. I suspect it's to do with
the model method working from the data rather than form values, but I
don't know enough about the admin area to work out how to change that.
Thanks for the help, but I think in this case I think I'll just have
to get admin users to select both categorisations rather than
automating it.
Kind regards,
-Alastair
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