On Wednesday, December 15, 2010 1:34:15 PM UTC, josch wrote:
>
> Hallo,
>
> I know, that the normal way to do that is to write the return value of
> the method to the foreign model, always when a model that affects the
> return value changes, and than order by that value of the model.
>
> But I have a model whoose objects gets a specific state after they are
> older than a specific number of days. And i don`t want to use a
> cronjob or something like that to update the foreign model`s value.
>
> So, can someone tell me, how I can order a query set by one of the
> function of it`s models, in a pinch by reordering the obecjts in a new
> object array or some kind like that.
>
> There are not a lot of records I have to order, so I think there is no
> performance problem for my kind of application.
>
> Thank you!
You can convert the queryset to a list, then call the standard list sort
method on it, passing the method as the key:
results = MyModel.objects.filter(criteria=whatever)
results = list(results)
results.sort(key=lambda x: x.my_method())
Obviously, as you note, this is not as efficient as doing the sorting in the
database, but for small numbers of objects it should be acceptable.
--
DR.
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