improvements

README.md

@@ -104,7 +104,15 @@ You can set your custom reporter by defining a class responding to `#report` met
 ```ruby
 class MyReporter
   def report(title, created_records)
-    # do actual reporting
+    title # => "controller#action"
+    created_records # => [#<ColumnsTrace::CreatedRecord>]
+    created_records.each do |record|
+      record.model # class of ActiveRecord model
+      record.accessed_fields  # array of accessed fields
+      record.unused_fields # array of unused fields
+      record.backtrace # array of strings
+      record.record # ActiveRecord model instance
+    end
   end
 end
 

lib/columns_trace/created_record.rb

@@ -3,18 +3,37 @@
 module ColumnsTrace
   # Class that is used to store metadata about created ActiveRecord records.
   class CreatedRecord
-    attr_reader :model, :record, :backtrace
+    # Model class
+    # @return [Class]
+    #
+    attr_reader :model
+
+    # Model instance
+    # @return [ActiveRecord::Base]
+    #
+    attr_reader :record
+
+    # Backtrace where the instance was created
+    # @return [Array<String>]
+    #
+    attr_reader :backtrace
 
     def initialize(record, backtrace)
       @model = record.class
       @record = record
       @backtrace = backtrace
     end
 
+    # Get accessed fields on model instance
+    # @return [Array<String>]
+    #
     def accessed_fields
-      record.accessed_fields
+      @accessed_fields ||= record.accessed_fields
     end
 
+    # Get unused fields on model instance
+    # @return [Array<String>]
+    #
     def unused_fields
       # We need to store this into local variable, because `record.attributes`
       # will access all attributes.