Have to opt in with #cache_key

lib/active_model/serializer.rb

@@ -441,17 +441,7 @@ module ActiveModel
     end
 
     def perform_caching?
-      perform_caching && cache && cache_key
-    end
-
-    # Override this method if you want to create a key based on associations
-    # Here's an example: your serializer has associations and the scope
-    #
-    # def cache_key
-    #   [ object, scope, scope.comments ]
-    # end
-    def cache_key
-      object.try :cache_key
+      perform_caching && cache && try(:cache_key)
     end
 
     def expand_cache_key(*args)

test/caching_test.rb

@@ -30,10 +30,6 @@ class CachingTest < ActiveModel::TestCase
       %w(ruby)
     end
 
-    def cache_key
-      name
-    end
-
     def read_attribute_for_serialization(name)
       send name
     end
@@ -61,6 +57,10 @@ class CachingTest < ActiveModel::TestCase
       def self.to_s
         'serializer'
       end
+
+      def cache_key
+        object.name
+      end
     end
 
     serializer.cache = NullStore.new
@@ -82,6 +82,10 @@ class CachingTest < ActiveModel::TestCase
       def self.to_s
         'serializer'
       end
+
+      def cache_key
+        object.name
+      end
     end
 
     serializer.cache = NullStore.new