Re: Django model manager "live" object issues

Indeed, I have just updated this to use class-based generic-views and
it appears to be working as designed:

from django.conf.urls.defaults import *

from django.views.generic import ListView, RedirectView

from application.news.models import Article, Category

urlpatterns = patterns('',
(r'^$', RedirectView.as_view(url="all")),

url(r'^all/$', ListView.as_view(
model=Article,
), name="news_all"),
)

So here the queryset is not cached and using the model=Article
specification means that the default query is run, in my case the
"live" query.

Cheers
Jay

On May 30, 1:57 pm, James Hargreaves <james.hargrea...@gmail.com>
wrote:
> Hi Kirill,
>
> Thanks for your response and sorry for my tardiness in replying!
>
> I think you are right - my queryset is cached in the view, as my
> urls.py looks like this:
>
> from django.conf.urls.defaults import *
> from django.views.generic.simple import redirect_to
> from django.views.generic.list_detail import object_list,
> object_detail
>
> from application.news.models import Article, Category
> from application.news.views import news_article_detail
>
> urlpatterns = patterns('',
>     (r'^$',
>         redirect_to, { 'url' : 'all' }),
>
>     (r'^all/$',
>         object_list, {
>             'queryset' : Article.live.all(),
>         }, 'news_all'),
>
>     (r'^(?P<slug>[-\w]+)/$',
>         object_detail, {
>             'queryset' : Category.objects.all(),
>         }, 'news_category'),
>
>     # the article should appear under the category menu item
>     (r'^(?P<category_slug>[-\w]+)/(?P<slug>[-\w]+)/$',
>         news_article_detail, {
>             'queryset' : Article.live.all(),
>         }, 'news_article'),
> )
>
> Note - I realise this is using function-based generic-views and I am
> going to change this to class-based shortly, in the hope that this
> will fix the issue.
>
> Anyway, so the call to Article.live.all() will create a QuerySet and
> this is stored in the queryset attribute for the "news_all" and
> "news_article" views. I don't know how to create my view so that the
> filter is done at runtime instead of compile time. I could of course
> do the check in my view code, but that's not great programming
> practice and also bad from a performance perspective.
>
> Any thoughts???
>
> Thanks
> Jay
>
> On May 19, 10:36 pm, Kirill Spitsin <t...@0x746e.org.ua> wrote:
>
>
>
>
>
>
>
> > On Wed, May 18, 2011 at 11:45:46PM -0700,JamesHargreaveswrote:
>
> > ...
>
> > > Firstly, when I query for LIVE objects in my view via
> > > Article.live.all() if I refresh the page repeatedly I can see (in
> > > MYSQL logs) the same database query being made with exactly the same
> > > date in the where clause - ie - the datetime.datetime.now() is being
> > > evaluated at compile time rather than runtime. I need the date to be
> > > evaluated at runtime.
>
> > I can't reproduce such behavior.  `.get_query_set()` is evaluted when
> > queryset is returned from manager, so, maybe, you cache queryset
> > somewhere in your view?
>
> > > Secondly, when I use the articles_set method on the Category object
> > > this appears to work correctly - the datetime used in the query
> > > changes each time the query is run - again I can see this in the logs.
> > > However, I am not quite sure why this works, since I don't have
> > > anything in my code to say that the articles_set query should return
> > > LIVE entries only!?
>
> > The first manager defined on model is interepted as "default manager".
> > You probably want to put line with `live` manager after `objects`
> > manager in `Article` declaration.
>
> > > Finally, why is none of this being cached?
>
> > Not quite so, QuerySet has a cache [1].
>
> > .. [1]http://docs.djangoproject.com/en/1.3/topics/db/queries/#caching-and-q...
>
> > --
> > Kirill Spitsin

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