Practiaal rules for Django MiddleWare ordering?
- by o_O Tync
The official documentation is a bit messy: 'before' & 'after' are used for ordering MiddleWare in a tuple, but in some places 'before'&'after' refers to request-response phases. Also, 'should be first/last' are mixed and it's not clear which one to use as 'first'.
I do understand the difference.. however it seems to complicated for a newbie in Django.
Can you suggest some correct ordering for builtin MiddleWare classes (assuming we enable all of them) and — most importantly — explain WHY one goes before/after other ones?
here's the list, with the info from docs I managed to find:
UpdateCacheMiddleware
Before those that modify 'Vary:' SessionMiddleware, GZipMiddleware, LocaleMiddleware
GZipMiddleware
Before any MW that may change or use the response body
After UpdateCacheMiddleware: Modifies 'Vary:'
ConditionalGetMiddleware
Before CommonMiddleware: uses its 'Etag:' header when USE_ETAGS=True
SessionMiddleware
After UpdateCacheMiddleware: Modifies 'Vary:'
Before TransactionMiddleware: we don't need transactions here
LocaleMiddleware, One of the topmost, after SessionMiddleware, CacheMiddleware
After UpdateCacheMiddleware: Modifies 'Vary:'
After SessionMiddleware: uses session data
CommonMiddleware
Before any MW that may change the response (it calculates ETags)
After GZipMiddleware so it won't calculate an E-Tag on gzipped contents
Close to the top: it redirects when APPEND_SLASH or PREPEND_WWW
CsrfViewMiddleware
AuthenticationMiddleware
After SessionMiddleware: uses session storage
MessageMiddleware
After SessionMiddleware: can use Session-based storage
XViewMiddleware
TransactionMiddleware
After MWs that use DB: SessionMiddleware (configurable to use DB)
All *CacheMiddleWare is not affected (as an exception: uses own DB cursor)
FetchFromCacheMiddleware
After those those that modify 'Vary:' if uses them to pick a value for cache hash-key
After AuthenticationMiddleware so it's possible to use CACHE_MIDDLEWARE_ANONYMOUS_ONLY
FlatpageFallbackMiddleware
Bottom: last resort
Uses DB, however, is not a problem for TransactionMiddleware (yes?)
RedirectFallbackMiddleware
Bottom: last resort
Uses DB, however, is not a problem for TransactionMiddleware (yes?)
(I will add suggestions to this list to collect all of them in one place)
