On Thu, 2008-11-20 at 00:34 -0800, Nicola Murino wrote: [...] > I want populate a queryset for example with all table elements, for > example: > > nodes=Nodes.objects.select_related().all() > > I want this query is performed so for example i do > > print nodes > > next I want to do nodes.filter(...=...) > > when I filter another query is done, why? the queryset already have > all the needed info, so why hit the database?
Because that's the way querysets work. In this case, *maybe* (and only maybe) do you have all the information needed to do the subsequent filtering, but usually you will not. You are creating a new queryset, which corresponds to a new query against the database. If you don't evaluate that new queryset, it won't access the database, but it doesn't use the previous results in the cache, since that would lead to inconsistent results. Every time you create a new queryset -- and that means each time you add a filter -- if you access the results of that queryset, it will talk to the database to get the results. Regards, Malcolm --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
