refactor batch_cache code

lib/active_model/serializer/adapter/attributes.rb

@@ -24,18 +24,31 @@ def fragment_cache(cached_hash, non_cached_hash)
         private
 
         def serializable_hash_for_collection(options)
-          if options[:batch_cache].blank? && ActiveModelSerializers.config.cache_store.present?
-            keys = CachedSerializer.object_cache_keys(serializer, @include_tree)
-            if keys.present?
-              values = ActiveModelSerializers.config.cache_store.read_multi(*keys)
-
-              options.merge!(batch_cache: values)
-            end
-          end
+          options.merge!(batch_cache(options))
 
           serializer.map { |s| Attributes.new(s, instance_options).serializable_hash(options) }
         end
 
+        # Read cache from cache_store, and set those into options[:batch_cache]
+        # @return [Hash] a batch of cache
+        def batch_cache(options)
+          return {} if options[:batch_cache].present? || ActiveModelSerializers.config.cache_store.blank?
+
+          keys = CachedSerializer.object_cache_keys(serializer, @include_tree)
+
+          return {} if keys.blank?
+
+          { batch_cache: ActiveModelSerializers.config.cache_store.read_multi(*keys) }
+        end
+
+        # Get serializer from options[:batch_cache].
+        # @return [Hash] cached attributes
+        def batch_cached_serializer(options)
+          return unless options[:batch_cache].present?
+
+          options[:batch_cache][CachedSerializer.new(serializer).cache_key]
+        end
+
         def serializable_hash_for_single_resource(options)
           resource = resource_object_for(options)
           relationships = resource_relationships(options)
@@ -65,13 +78,9 @@ def include_meta(json)
         end
 
         def resource_object_for(options)
-          if options[:batch_cache].present?
-            cache_key = CachedSerializer.new(serializer).cache_key
-
-            value = options[:batch_cache][cache_key]
+          batch_cached_serializer_attributes = batch_cached_serializer(options)
 
-            return value if value.present?
-          end
+          return batch_cached_serializer_attributes if batch_cached_serializer_attributes.present?
 
           cache_check(serializer) do
             serializer.attributes(options[:fields])

test/serializers/cache_test.rb

@@ -161,6 +161,24 @@ def test_object_cache_keys
         assert actual.any? { |key| key =~ %r{writer/author-\d+} }
       end
 
+      def test_batch_cache
+        serializer = CollectionSerializer.new([@comment, @comment])
+
+        Timecop.freeze(Time.now) do
+          render_object_with_cache(@comment)
+
+          batch_cache = ActiveModel::Serializer::Adapter::Attributes.new(serializer).send(:batch_cache, {})[:batch_cache]
+
+          assert_equal batch_cache[@comment.cache_key], Comment.new(id: 1, body: 'ZOMG A COMMENT').attributes
+          assert_equal batch_cache[@comment.post.cache_key], Post.new(id: "post", title: 'New Post', body: 'Body').attributes
+
+          writer = @comment.post.blog.writer
+          writer_cache_key = "writer/#{writer.id}-#{writer.updated_at.strftime("%Y%m%d%H%M%S%9N")}"
+
+          assert_equal batch_cache[writer_cache_key], Author.new(id: "author", name: 'Joao M. D. Moura').attributes
+        end
+      end
+
       def test_serializer_file_path_on_nix
         path = '/Users/git/emberjs/ember-crm-backend/app/serializers/lead_serializer.rb'
         caller_line = "#{path}:1:in `<top (required)>'"