Does not support custom User model permissions

[jhnbkr]

I implemented django-clearcache into our project and came across an issue where it expected our User model to have the attribute is_superuser.

We have a custom User model and permissions setup that does not implement this attribute.
My bandaid was to implement a property for is_superuser that proxies our internal permissions validation check.

One solution could be to add a setting that defines the target User attribute name which defaults to is_superuser.

[YPCrumble]

@timonweb I'm having a similar issue, in that by using the is_superuser permission, it means that I would have to grant permission to everything in my entire site for a user to be able to clear the cache, which severely limits the number of users I allow to clear the cache.

One option would be to replace request.user.is_superuser with request.user.is_staff, which is a tradeoff in that it allows any user with access to the admin to clear the cache, but doesn't require superuser privileges to clear the cache.

My current solution is to implement my own version of clearcache's URL and call a custom subclass of ClearCacheAdminView, but I'm a little worried that future updates to the library might make this no longer work, or worse, leak the cache clearing permission somehow.

class CustomClearCacheAdminView(ClearCacheAdminView):
    """
    Override the default clearcache admin to allow is_staff to clear the cache.
    """
    def test_func(self):
        return self.request.user.is_staff

path(
    "admin/clearcache/",
    CustomClearCacheAdminView.as_view(),
    name="clearcache_admin"
),

The ideal solution might be to implement a custom permission that would automatically be added to the is_superuser permission, but could also be added to specific Group entries on an as-needed basis.

I'd be happy to work on a PR, or document the above subclass workaround, if any of these seems most helpful!

[fabiocaccamo]

@jhnbkr @YPCrumble @bernardoduarte @tehfink @bramski since the development of this library seems to be stale and the developer does not respond in the issues, I published a tiny yet powerful alternative.

Here the repo in case you are interested: https://github.com/fabiocaccamo/django-cache-cleaner