Refs #5815, #31938, #34271 -- Created invalidate_view_cache function … #19946

rjnocelli · Oct 12, 2025

Trac ticket number

Branch description

At the moment there is not an 'easy' way to invalidate cached view responses from Django code. This PR introduces an utility function called invalidate_view_cache which allows you to do so using the relative path (request object takes care of putting together the rest of the URL).

Checklist

This PR targets the main branch.
The commit message is written in past tense, mentions the ticket number, and ends with a period.
I have checked the "Has patch" ticket flag in the Trac system.
I have added or updated relevant tests.
I have added or updated relevant docs, including release notes if applicable.
I have attached screenshots in both light and dark modes for any UI changes.

github-actions · Oct 12, 2025

Hello! Thank you for your contribution 💪

As it's your first contribution be sure to check out the patch review checklist.

If you're fixing a ticket from Trac make sure to set the "Has patch" flag and include a link to this PR in the ticket!

If you have any design or process questions then you can ask in the Django forum.

Welcome aboard ⛵️!

…ction to manually invalidate cache key. Thanks Laurent Tramoy for the implementation idea and Carlton Gibson for the support.

carltongibson · Oct 13, 2025

Hey @rjnocelli — Welcome aboard! ⛵️— Nice hustle turning your work into a PR over the weekend. (You can assign the ticket to yourself on Trac 🙂)

Let me read it through and give an initial feedback. (We don't currently use type annotations in Django itself, so we'll drop those, and docs would be needed, etc — but we can refine towards all that.)

Nice one! 👊

carltongibson

Hey @rjnocelli — I had a first look.

Can you add some test cases for the vary_header argument, showing that in action?

We'll need then to adjust the docstring a little and add docs, but seems pretty straightforward. Nice 👍

carltongibson · Oct 13, 2025

django/utils/cache.py

+    vary_headers should be a dict of every header used for this particular view
+    In local environment, we have two defined renderers (default of DRF),
+    thus DRF adds `Accept` to the Vary headers


@rjnocelli Can you add tests showing this in action?

yes, definitely!

carltongibson · Oct 13, 2025

django/utils/cache.py

+    path: str = None,
+    request: WSGIRequest = None,
+    vary_headers: Optional[Dict[str, str]] = None,
+    key_prefix: Optional[str] = None,
+) -> Annotated[int, "Number of cache keys deleted"]:


We should remove the annotations.

thanks, will do!

carltongibson · Oct 13, 2025

django/utils/cache.py

+    Note: If LocaleMiddleware is used,
+    we'll need to use the same language code as the one in the cached request


This probably needs a test case too.

Both the decorator and get_cache_key function rely on the same underlying logic in _generate_cache_key which accounts for configuration settings.USE_I18N. Since this logic is implicit to the generation and retrieval of the cache key in this workflow, is a test really needed here? It might make sense to add to possibility to delete all locale variations of a key (something similar to what Laurent Tramoy propposed on ticket 31938) but this will require more work since not all cache backends support key search by pattern (I think Redis scan function would work for this).

OK, not sure immediately. Maybe a test isn't needed...

I was mostly thinking for the docs. We're going to need to give examples for folks to know how to use this function, and given that it's worth a comment, it's probably worth an examples too.

(Start with the normal vary versions and then we can see what docs we come up with)

rjnocelli · Oct 14, 2025

I've applied some new changes:

removed typing
removed function parameters which I think are not relevant for the scope of this implementation
added documentation
added two new tests to cover cases for Vary headers and key prefix missmatch

carltongibson

Thanks for the updates @rjnocelli. I've just left a few more discursive comments. (They're status Maybe 🤔 rather than more than that.)

I checked the flag on the ticket: looking good. Ready for a review from someone else now.

(I'm really excited about this. I'm going to have to pull it into my personal project so that I can stop flushing my cache entirely every time I spot a typo 💃)

carltongibson · Oct 16, 2025

django/utils/cache.py

+    If there is no headerlist stored, the page needs to be rebuilt, so this
+    function returns ``None``.


This seems unrelated. Could either be dropped or merged as a separate clean up. (Pending Fellow decisions)

Yes, I'll roll this one back.

carltongibson · Oct 16, 2025

django/utils/cache.py

+    Delete a view cache key based on either a relative URL (``path``)
+    or a request object (``request``).


Does "view cache" relate to cache_page clearly enough? Maybe...

Suggested change

Delete a view cache key based on either a relative URL (``path``)

or a request object (``request``).

Delete a cached page key based on either a relative URL (``path``)

or a request object (``request``).

carltongibson · Oct 16, 2025

django/utils/cache.py

    return t[0].lower(), True
+
+
+def invalidate_view_cache(path=None, request=None, key_prefix=None, cache=None):


I wonder if we want just a request parameter, which could be a path, then converted in the same code block as below? 🤔

carltongibson · Oct 16, 2025

django/utils/cache.py

+    If both are given, ``path`` takes precedence.
+    """
+    if not request:
+        assert path is not None, "either `path` or `request` arguments needed"


Raise a ValueError (?) here, and test for the exception. (Rather than an assertion, to match Django code style.)

rjnocelli · Oct 16, 2025

Hi @carltongibson! Here are few comments regarding my latest changes:

I've removed path parameter. Now request parameter accepts a HttpRequest object or a relative path. Regarding the latter, I've noticed that the request factory "stringyfies" any path/url type so it is very unlikely for it to rise a ValueError therefore I don't see the value of adding a testcase for this. Obviously passing a dict or list as path does not make sense at all so it is down to the user to call the function with the proper types.
I've rolled back get_cache_key documentation to it's original one.
I've added a new test using a ASGIRequest instead of a WSGIRequest. Please let me know if this does not add value at all and I'll remove it.

Looking forward hearing back from you! cheers!

carltongibson · Oct 17, 2025

Great. good effort @rjnocelli.

I want to wait for someone else to take a look now. It's in the right ballpark, but other eyes. I looked at the flags on Trac, and they were set right, so this ticket will appear on the review queue.

rjnocelli force-pushed the invalidate_cache_key_function branch from db53bae to 063c5ee Compare October 12, 2025 17:22

Refs django#5815, #31938, #34271 -- Created invalidate_view_cache fun…

20e2676

…ction to manually invalidate cache key. Thanks Laurent Tramoy for the implementation idea and Carlton Gibson for the support.

rjnocelli force-pushed the invalidate_cache_key_function branch from 063c5ee to 20e2676 Compare October 12, 2025 17:26

carltongibson reviewed Oct 13, 2025

View reviewed changes

jacobtylerwalls added the Django on the Med 🏖️ label Oct 13, 2025

rjnocelli added 4 commits October 13, 2025 22:39

remove type annotations

ec6612b

add test for response with Vary headers case

951d78a

remove ignore_headers argument from get_cache_key

b530fd2

add documentation

dc07fac

carltongibson reviewed Oct 16, 2025

View reviewed changes

rjnocelli added 2 commits October 16, 2025 20:38

apply review comments

cbff6d1

add test to cover case invalidate_view_cache with async request

32e45ff

ammend docs

81d76f9

		Note: If LocaleMiddleware is used,
		we'll need to use the same language code as the one in the cached request

		If there is no headerlist stored, the page needs to be rebuilt, so this
		function returns ``None``.

		Delete a view cache key based on either a relative URL (``path``)
		or a request object (``request``).

		return t[0].lower(), True


		def invalidate_view_cache(path=None, request=None, key_prefix=None, cache=None):

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