cache_control() "max_age" overrides cache_page() "timeout"

[Danny Flack]

If you decorate a view with both cache_control(max_age=3600) and cache_page(timeout=3600*24), the server side cache uses the max_age value instead of the timeout value.

The comments in UpdateCacheMiddleware.process_response() indicate it's trying to set the timeout by first looking for the max-age header before reverting to the default cache_timeout :

Try to get the timeout from the "max-age" section of the "Cache-
Control" header before reverting to using the default cache_timeout
length.

However, cache_page(timeout=3600*24) is explicitly setting the cache_timeout so that is what should be used.

In summary, if a user wants the client-side cache to be shorter-lived than the server-side cache, it is currently not possible using these two decorators.

[Carlton Gibson]

OK, yes, this seems legitimate.

Current behaviour was deliberately introduced in #5813 (f2f6e70b08b1142055e33e75f58cfe7fbb5d868f).

(Looking at tickets for Core+(Cache+system) there are a few on similar topics, though not exactly so.)

[Danny Flack]

I have an idea of how to solve this but I assume the core developers have a better understanding of why it was done this way in the first place, and what else it'll affect. Is it worth me submitting a patch? Please let me know how I can help.

[Carlton Gibson]

Hi Danny.

Perhaps a post to the DevelopersMailingList, explaining as clearly as possible what's going on, and your idea, would be the best way to go.
That way, you're likely to get the feedback you need.

Thanks!

[Danny Flack]

Thanks. I posted a new topic on that list. ​https://groups.google.com/forum/#!topic/django-developers/BwTZFMpqd6U

[Flavio Curella]

​PR on github

[Mariusz Felisiak <felisiak.mariusz@…>]

In d08d4f4:

Fixed #30765 -- Made cache_page decorator take precedence over max-age Cache-Control directive.