Thanks for the thoughts, Stuart. On Dec 23, 2:08 pm, Stuart Laughlin <stu...@bistrotech.net> wrote: > On Dec 22, 9:01 am, ChrisCurvey<ccur...@gmail.com> wrote: > > > The short version: when processing a request, does Django *always* > > collect session information from the session store before starting the > > view? > > Yes. However note that django only saves to the session database when > the session has been modified. It doesn't seem like that's affecting > you, but I can't be sure.
So long as Django is auto-saving and auto-fetching, I think I should be OK. I guess I could set up something to monitor the database activity. > > http://www.djangobook.com/en/2.0/chapter14/ > > > The long version: > > > i have an application that makes heavy use ofAJAX. When a user > > changes something on the page, the page fires anAJAXPOST to apply > > the changes to the database, then a series ofAJAXGETs to refresh > > other portions of the page. > > You say, "then a series ofAJAXGETs" but when is "then"? Presumably > in the post's callback function? Because otherwise you have no > guarantee that the POST completes before the GETs fire. The query is fired from jQuery, and here's my code. (I realize this is getting a little far from being Django-specific) $.ajax({url: "/hold_time_cost/" , data: {tran_num : $(this).attr('tran_num'), value : checked, file_number : file_number}, type: "POST", async: false, cache: false, complete: function(request, status) { get_unbilled_costs(file_number); get_held_costs(file_number); } }); > > > > Some of the GETs are expensive, so I have some process_response() > > middleware that caches the HTML generated by the GET in the Django > > session. (It's the standard database session store.) I also have > > some process_request() middleware that either returns the cached HTML > > if it can, or invalidates the cache on any POST. > > > Just to add to the fun, I have a four identical Django/mod_wsgi > > instances running behind a round-robin load balancer. So the POST > > request might get handled by Django1, the first GET by Django2, the > > second GET by Django3, and so on. > > > My problem is that sometimes the results of the POST are not visible > > in the results of the GET. The problem is intermittent, which is > > leading me to point the finger at my cacheing strategy. My assumption > > was that Django would reload the session from the database every time > > before starting my view code, but I'm wondering if that is not true > > (or if there is some other issue that I'm not thinking about). > > Yes, your caching seems a likely culprit, and so does the asynchronous > nature of youAJAX(but it seems like you've got a handle on that > part). I haven't thought through the load balancer bit yet, but > presumably they are all using the same cache / database / session > store..? I'm wondering if maybe I should futz with using the django.contrib.sessions.backends.cached_db for a session engine. > > --Stuart -- Chris -- 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 django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
