Fix favorite_lists returning null on cache miss and add regression coverage

care/emr/api/viewsets/favorites.py

@@ -41,8 +41,8 @@ def favorite_lists(self, request, *args, **kwargs):
             favorite_lists_cache_key(user, self.FAVORITE_RESOURCE, facility)
         )
         if favorite_lists is None:
-            favorite_list_obj = list(
-                set(
+            favorite_lists = list(
+                dict.fromkeys(
                     UserResourceFavorites.objects.filter(
                         user=user,
                         resource_type=self.FAVORITE_RESOURCE,
@@ -54,8 +54,9 @@ def favorite_lists(self, request, *args, **kwargs):
             )
             cache.set(
                 favorite_lists_cache_key(user, self.FAVORITE_RESOURCE, facility),
-                favorite_list_obj,
+                favorite_lists,
             )
+
         return Response({"lists": favorite_lists})
 
     @action(detail=True, methods=["POST"])
@@ -64,14 +65,15 @@ def add_favorite(self, request, *args, **kwargs):
         favorite_list = request_data.favorite_list
         obj = self.get_object()
         user = self.request.user
+
         favorite_list_obj, _ = UserResourceFavorites.objects.get_or_create(
             user=user,
             favorite_list=favorite_list,
             resource_type=self.FAVORITE_RESOURCE,
             facility=self.retrieve_facility_obj(obj),
         )
+
         favorite_list_obj.favorites.insert(0, obj.id)
-        # trim favorites list to max allowed
         favorite_list_obj.favorites = list(dict.fromkeys(favorite_list_obj.favorites))[
             : settings.MAX_FAVORITES_PER_LIST
         ]
@@ -85,16 +87,20 @@ def remove_favorite(self, request, *args, **kwargs):
         obj = self.get_object()
         user = self.request.user
         facility = self.retrieve_facility_obj(obj)
+
         favorite_list_obj = UserResourceFavorites.objects.filter(
             user=user,
             favorite_list=favorite_list,
             resource_type=self.FAVORITE_RESOURCE,
             facility=facility,
         ).first()
+
         if not favorite_list_obj:
             raise ValidationError("Favorite List not found")
+
         favorite_list_obj_favorites = dict.fromkeys(favorite_list_obj.favorites)
         favorite_list_obj_favorites.pop(obj.id, None)
+
         if len(favorite_list_obj_favorites) == 0:
             cache.delete(
                 favorite_lists_cache_key(user, self.FAVORITE_RESOURCE, facility)
@@ -109,6 +115,7 @@ def remove_favorite(self, request, *args, **kwargs):
             )
             UserResourceFavorites.objects.filter(id=favorite_list_obj.id).delete()
             return Response({})
+
         favorite_list_obj.favorites = list(favorite_list_obj_favorites)
         favorite_list_obj.save(update_fields=["favorites"])
         return Response({})

care/emr/tests/test_favorites_api.py

@@ -239,6 +239,18 @@ def test_list_favorites_list(self):
             )
         )
 
+    def test_favorite_lists_returns_list_on_first_call(self):
+        cache.delete(self.favorite_list_cache_key)
+
+        response = self.client.get(self.base_url + "favorite_lists/")
+
+        self.assertEqual(response.status_code, 200, response.content)
+        self.assertIn("lists", response.data)
+        self.assertEqual(response.data["lists"], [])
+
+        data = cache.get(self.favorite_list_cache_key)
+        self.assertEqual(data, [])
+
     def test_list_ordered_by_favorites(self):
         charge_item = self.create_charge_item_definition()
         charge_item_2 = self.create_charge_item_definition()

care/users/api/viewsets/plug_config.py

@@ -19,7 +19,7 @@ class PlugConfigViewset(
     def list(self, request, *args, **kwargs):
         # Cache data and return
         response = cache.get(self.cache_key)
-        if not response:
+        if response is None:  # cache miss; allow cached empty list
             serializer = self.get_serializer(self.get_queryset(), many=True)
             response = serializer.data
             cache.set(self.cache_key, response)