That's what I thought- But why not just qs[0]? Doesn't qs[:1] and qs[0] both cause a LIMIT 1 on the query? It seems that the [:1] is unnecessary. I would expect both to raise IndexError.
On Wed, May 15, 2013 at 11:39 PM, Alex Ogier <[email protected]> wrote: > Significantly better. The latter method loads every single model in the > queryset into Python, potentially the whole database! > On May 15, 2013 9:24 PM, "Lee Trout" <[email protected]> wrote: > >> Is qs[:1][0] better form than list(qs)[0]? >> >> >> On Wed, May 15, 2013 at 7:48 AM, Selwin Ong <[email protected]> wrote: >> >>> I've updated the first() and last() to not accept any arguments. Please >>> review it and let me know if there's anything else I need to change. >>> Hopefully this can get merged in during the sprints and make it into 1.6 :). >>> >>> The pull request is here: https://github.com/django/django/pull/1056 >>> >>> Best, >>> Selwin >>> >>> On Monday, May 13, 2013 8:12:35 PM UTC+7, Michal Petrucha wrote: >>>> >>>> > > I initially modeled "first()" and "last()"'s behaviors to mimic >>>> > > "latest()", but in this new pull request, you can pass multiple >>>> field names >>>> > > into "first()" and "last()" so it behaves like "order_by()". It's >>>> more >>>> > > flexible and requires less typing, but I wonder if we should just >>>> get rid >>>> > > of the optional field arguments and rely on "order_by" for >>>> ordering. "There >>>> > > should be one-- and preferably only one --obvious way to do it". >>>> > >>>> > Considering "There should be one-- and preferably only one --obvious >>>> way to >>>> > do it", I definitely prefer to rely on order_by to do the ordering, >>>> not on >>>> > first. >>>> > >>>> > .order_by('name').first() >>>> > >>>> > is clear and readable in my opinion. >>>> >>>> My thoughts exactly, we already have one method that does ordering, I >>>> don't think it is necessary to make these methods incorporate that >>>> functionality. If we did, we might argue that other QuerySet >>>> operations could be supported as well and that would just result in a >>>> bloated API. Especially if there's no performance gain (the QuerySet >>>> would be cloned anyway), and it only saves a few lines of code. >>>> >>>> Also, skimming through this thread, I think there was a consensus on >>>> first() and last() not taking any ordering arguments, i.e. the first >>>> proposed syntax: >>>> >>>> .filter(last_name__startswith=**'b').order_by('last_name').**first() >>>> >>>> >>>> Michal >>>> >>> -- >>> 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 [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at >>> http://groups.google.com/group/django-developers?hl=en. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >>> >>> >> >> -- >> 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 [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at >> http://groups.google.com/group/django-developers?hl=en. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > -- > 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 [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/django-developers?hl=en > . > For more options, visit https://groups.google.com/groups/opt_out. > > > -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/django-developers?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
