Add paste_xxx_ids

lib/acts_as_pasting/pasted.rb

@@ -145,6 +145,10 @@ module ActsAsPasting
               self.paste_#{downcase}_list = ary
             end
 
+            def paste_#{downcase}_ids
+              pastings.where(type: "#{type_value}", pasteable_type: #{klass}.base_class.name).pluck(:pasteable_id)
+            end
+
             def paste_#{downcase}_list= ary, run_save: true
               ary = self.class.parsed_condition_ary(ary).select { |a| 
                 a.first == "#{base_class_name}"