cache learning object serializer

app/controllers/concerns/paginator.rb

 module Paginator
   extend ActiveSupport::Concern
 
-  def paginate (model)
-    set_header model
+  def paginate(model)
+    total_count model
     return model.limit(limit).offset(offset) if model.respond_to?('limit')
-    return model[offset..limit]
+    model[offset..limit]
   end
 
   private
 
   def limit
-    return 50 if params[:limit].blank?
+    return 12 if params[:limit].blank?
     params[:limit].to_i
   end
 
@@ -19,8 +19,7 @@ module Paginator
     params[:offset].to_i
   end
 
-  def set_header(model)
+  def total_count(model)
     headers['X-Total-Count'] = model.count
   end
-
 end

app/controllers/v1/learning_objects_controller.rb

@@ -13,7 +13,7 @@ class V1::LearningObjectsController < ApplicationController
   before_action :authorize!, except: [:create, :tagging, :untagging]
 
   def index
-    learning_objects = paginate LearningObject.includes(:tags, :publisher, :language, :license)
+    learning_objects = paginate LearningObject.includes(:tags, :publisher, :language, :license, :subjects, :educational_stages, :reviews)
     serializer = params[:obaa].nil? ? LearningObjectSerializer : LearningObjectObaaSerializer
     render json: learning_objects, each_serializer: serializer
   end

app/serializers/learning_object_serializer.rb

 class LearningObjectSerializer < ActiveModel::Serializer
+  cache key: 'learning_object', expires_in: 4.hours
+
   def default_location
     object.default_attachment.try(:retrieve_url)
   end