Misago/misago/cache/middleware.py

from django.utils.functional import SimpleLazyObject

from .versions import get_cache_versions


def cache_versions_middleware(get_response):
    """Sets request.cache_versions attribute with dict of cache versions."""
    def middleware(request):
        request.cache_versions = SimpleLazyObject(get_cache_versions)
        return get_response(request)

    return middleware