On Tue, Jul 30, 2013 at 6:06 PM, Florian Apolloner <f.apollo...@gmail.com>wrote:
> You can always do list(qs)]:-1] though… Although you really shouldn't [1]. As for the reasons for disallowing negative indexes, dcramer's comment in the ticket makes it clear: there is no way to infer what the last item in a query would be, except if you order it descendingly. For what is worth, production code should never rely on any kind of indexing that's not accompanied by an explicit order-by clause, as the default ordering is unrealiable -- at least in PostgreSQL[2], and I assume in other vendors as well[3]. In fact, one might even argue that it would make more sense to disallow any sort of indexing on querysets lacking an explicit .order_by(), in order to enforce best practices, although I would find that a little too strict. The specific one-off case of retrieving a single row for testing/developing/debugging would be best served by the use of .first() which orders by the primary_key by default[4], which therefore yields a different query from the one created by queryset indexing[5]. As it currently stands, the API mirrors the experience in writing a raw query insofar as it is *impossible* to retrieve the last row of a query without explicitly defining an order by clause. For this reason, I'm -1 on the proposed change. Cheers, AT [1] https://docs.djangoproject.com/en/dev/ref/models/querysets/ [2] http://www.postgresql.org/docs/9.2/static/queries-order.html [3] http://stackoverflow.com/a/5628674/447485 [4] https://docs.djangoproject.com/en/dev/ref/models/querysets/#first [5] http://dpaste.com/hold/1323698/ -- You received this message because you are subscribed to the Google Groups "Django developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To post to this group, send email to django-developers@googlegroups.com. Visit this group at http://groups.google.com/group/django-developers. For more options, visit https://groups.google.com/groups/opt_out.
