Only cache unauthenticated page views (#117)

2 files changed, 45 insertions, 7 deletions

diff --git a/core/decorators.py b/core/decorators.py
index fece564..dc8d4d2 100644
--- a/core/decorators.py
+++ b/core/decorators.py
@@ -1,34 +1,72 @@
+from collections.abc import Callable
 from functools import partial, wraps
+from typing import ParamSpecArgs, ParamSpecKwargs
 
+from django.http import HttpRequest
 from django.views.decorators.cache import cache_page as dj_cache_page
 
 from core.models import Config
 
+VaryByFunc = Callable[[HttpRequest, ParamSpecArgs, ParamSpecKwargs], str]
+
+
+def vary_by_ap_json(request, *args, **kwargs) -> str:
+    """
+    Return a cache usable string token that is different based upon Accept
+    header.
+    """
+    if request.ap_json:
+        return "ap_json"
+    return "not_ap"
+
+
+def vary_by_identity(request, *args, **kwargs) -> str:
+    """
+    Return a cache usable string token that is different based upon the
+    request.identity
+    """
+    if request.identity:
+        return f"ident{request.identity.pk}"
+    return "identNone"
+
 
 def cache_page(
     timeout: int | str = "cache_timeout_page_default",
     *,
-    per_identity: bool = False,
     key_prefix: str = "",
+    public_only: bool = False,
+    vary_by: VaryByFunc | list[VaryByFunc] | None = None,
 ):
     """
     Decorator for views that caches the page result.
     timeout can either be the number of seconds or the name of a SystemOptions
     value.
+    If public_only is True, requests with an identity are not cached.
     """
     _timeout = timeout
+    _prefix = key_prefix
+    if callable(vary_by):
+        vary_by = [vary_by]
 
     def decorator(function):
         @wraps(function)
         def inner(request, *args, **kwargs):
-            prefix = key_prefix
-            if per_identity:
-                identity_id = request.identity.pk if request.identity else "0"
-                prefix = f"{key_prefix or ''}:ident{identity_id}"
+            if public_only:
+                if request.user.is_authenticated:
+                    return function(request, *args, **kwargs)
+
+            prefix = [_prefix]
+
+            if isinstance(vary_by, list):
+                prefix.extend([vfunc(request, *args, **kwargs) for vfunc in vary_by])
+
+            prefix = "".join(prefix)
+
             if isinstance(_timeout, str):
                 timeout = getattr(Config.system, _timeout)
             else:
                 timeout = _timeout
+
             return dj_cache_page(timeout=timeout, key_prefix=prefix)(function)(
                 request, *args, **kwargs
             )
@@ -38,4 +76,4 @@ def cache_page(
     return decorator
 
 
-per_identity_cache_page = partial(cache_page, per_identity=True)
+cache_page_by_ap_json = partial(cache_page, vary_by=[vary_by_ap_json])
diff --git a/core/views.py b/core/views.py
index a09d925..2772eb8 100644
--- a/core/views.py
+++ b/core/views.py
@@ -18,7 +18,7 @@ def homepage(request):
         return LoggedOutHomepage.as_view()(request)
 
 
-@method_decorator(cache_page(), name="dispatch")
+@method_decorator(cache_page(public_only=True), name="dispatch")
 class LoggedOutHomepage(TemplateView):
 
     template_name = "index.html"