Hi Daniel, I don't think a warning is necessary here as it's fairly standard Python.
To explain: the timezone.now() is evaluated at module level – ie only once when the Python module is imported – which explains the behaviour that you're experiencing. If you like you can submit a documentation PR with some suggestions but others may also doubt the value of adding a warning given that the very next section explains how to do dynamic filtering. Personally I think by the time you get to advanced Django such as this, Python experience is assumed :) Regards, David On Sun, 30 Oct 2022 at 00:02, Daniel Gayoso González <danigayo...@gmail.com> wrote: > Hello, > > Following the example in > https://docs.djangoproject.com/en/4.1/topics/class-based-views/generic-display/#viewing-subsets-of-objects > I tried the following > > class BookListView(ListView): > model = Book > queryset = Book.objects.filter(publication_date__lte=timezone.now()) > > I found that this code snippet to retrieve only books that has the > publication date before today (assuming that could be books with > publication date in the future) not work as I would expected. > > After some digging, I found that timezone.now() it's cached when server > starts up (in a production environment), so this query filter by the date > the server was started. So the solution is to use a dynamic filtering. > > Could be a good idea to include some warning about this in the > documentation? > > Thanks, > Daniel > > -- > You received this message because you are subscribed to the Google Groups > "Django developers (Contributions to Django itself)" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to django-developers+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/CAHLCT5d3Dz3KTfpxhLQAUZjruhRLgb_XKbUKdv7VgHW_-VVfCg%40mail.gmail.com > <https://groups.google.com/d/msgid/django-developers/CAHLCT5d3Dz3KTfpxhLQAUZjruhRLgb_XKbUKdv7VgHW_-VVfCg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/CADyZw-59A5U0pLOuZ%2BxdfHp%3Dq%3Ddwgw%2BG_GFaRYQAxfdytX6%2B5Q%40mail.gmail.com.
