Deprecate cache argument

Author: Ryan P Kilby

rest_framework_filters/backends.py

@@ -5,13 +5,12 @@
 
 class DjangoFilterBackend(rest_framework.filters.DjangoFilterBackend):
     default_filter_set = FilterSet
-    _related_filterset_cache = {}  # set to None to disable cache propagation
 
     def filter_queryset(self, request, queryset, view):
         filter_class = self.get_filter_class(view, queryset)
 
         if filter_class:
-            cache = self._related_filterset_cache
-            return filter_class(request.query_params, queryset=queryset, cache=cache).qs
+            subset_class = filter_class.get_subset(request.query_params)
+            return subset_class(request.query_params, queryset=queryset).qs
 
         return queryset

rest_framework_filters/filterset.py

@@ -3,6 +3,7 @@
 
 from collections import OrderedDict
 import copy
+import warnings
 
 from django.db import models
 from django.db.models.constants import LOOKUP_SEP
@@ -61,7 +62,12 @@ class FilterSet(six.with_metaclass(FilterSetMetaclass, filterset.FilterSet)):
     _subset_cache = {}
 
     def __init__(self, *args, **kwargs):
-        self._related_filterset_cache = kwargs.pop('cache', {})
+        if 'cache' in kwargs:
+            warnings.warn(
+                "'cache' argument is deprecated. Override '_subset_cache' instead.",
+                DeprecationWarning, stacklevel=2
+            )
+            self.__class__._subset_cache = kwargs.pop('cache', None)
 
         super(FilterSet, self).__init__(*args, **kwargs)
 

tests/test_deprecations.py

@@ -0,0 +1,21 @@
+
+import warnings
+from django.test import TestCase
+
+from .filters import UserFilter
+
+
+class FilterSetCacheDeprecationTests(TestCase):
+
+    def test_notification(self):
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("always")
+
+            cache = {}
+
+            UserFilter({}, cache=cache)
+
+            self.assertEqual(len(w), 1)
+            self.assertTrue(issubclass(w[-1].category, DeprecationWarning))
+
+            self.assertIs(UserFilter._subset_cache, cache)