LocaleMiddleware breaks caching
Harm Verhagen
I found out using i18n with django breaks caching completely.
(reverse proxy & browser caching, that is).
Initially I filed a bug about this [1], But its more complicated that
just a bug. Therefor I post the topic here.
Whats the problem:
enabling django.middleware.locale.LocaleMiddleware, makes your
complete site un-cachable, as _every_ response gets automatically
the following http header "Vary: Cookie"
(as LocaleMiddleware reads the session -> session.accessed becomes
True -> Vary: Cookie gets added).
"Vary: Cookie" effectively means, with all current browsers, that
the browser will not, never cache the page.
As discussed in [1], there is nothing you can do on views that
actually user i18n. They really do vary on the cookie.
Unfortunately, this happens for _every_ view, also the views that do
_not_ have anything to do with translations.
So I'm wondering if we can improve django locale handling, so that
only views that matter from an i18n point-of-view, get the "Vary:
Cookie" header.
some thoughts:
a) Make LocaleMiddleware configurable, which urls are i18n enabled and
which not. (but include/exclude patterns.
b) can we somehow make the reading of the session by LocaleMiddleware
so lazy, that only
when translation kicks in we touch the session.
Any thoughts?
Regards,
Harm