abstracting builder concern in base class

app/builders/attribute_builder.rb

+class AttributeBuilder < Builder
+  extend RepositoriesProxy
+
+  ##
+  # receive a list of ids and return a list of attributes
+  #
+  def self.build(attributes = [])
+    array = []
+    attributes = [attributes] if attributes.class == String
+    attributes.each do |attributes|
+      unless attributes['@rid'].blank?
+        o = Rails.cache.fetch(cache_key(attribute['@rid'], attribute['last_modified'])) unless attribute['last_modified'].blank?
+        o = attribute_repository.find attribute['@rid'] if o.nil?
+        array << o
+      end
+    end
+    array
+  end
+
+  def self.build_from_orientdb(args = {})
+    attribute = nil
+
+    unless args.nil?
+      # cache object when build
+      attribute = Rails.cache.fetch(cache_key(args['@rid'], args['last_modified']), expires_in: 12.hours) do
+        Attribute.new(
+            id: args['@rid'],
+            key: args['key'],
+            value: args['value']
+        )
+      end
+    end
+
+    attribute
+  end
+
+end

app/builders/builder.rb

+class Builder
+
+  protected
+
+  def self.cache_key(rid, last_modified)
+    rid + '/' + last_modified
+  end
+
+end
\ No newline at end of file

app/builders/collection_builder.rb

-class CollectionBuilder
+class CollectionBuilder < Builder
   extend RepositoriesProxy
 
   ##
@@ -42,10 +42,6 @@ class CollectionBuilder
     lo
   end
 
-  def self.cache_key(rid, last_modified)
-    rid + '/' + last_modified
-  end
-
   def self.map_rid_to_object(ids)
     return {'rid' => ids} if ids.class == String
 

app/builders/institution_builder.rb

-class InstitutionBuilder
+class InstitutionBuilder < Builder
   extend RepositoriesProxy
 
   ##
@@ -40,7 +40,4 @@ class InstitutionBuilder
     institution
   end
 
-  def self.cache_key(rid, last_modified)
-    rid + '/' + last_modified
-  end
 end

app/builders/learning_object_builder.rb

-class LearningObjectBuilder
+class LearningObjectBuilder < Builder
   extend RepositoriesProxy
 
   ##
@@ -50,7 +50,4 @@ class LearningObjectBuilder
     lo
   end
 
-  def self.cache_key(rid, last_modified)
-    rid + '/' + last_modified
-  end
 end