# Module that can be included into a model to make it easier to ignore database# columns.## Example:## class User < ActiveRecord::Base# include IgnorableColumn## ignore_column :updated_at# end#moduleIgnorableColumnextendActiveSupport::ConcernmoduleClassMethodsdefcolumnssuper.reject{|column|ignored_columns.include?(column.name)}enddefignored_columns@ignored_columns||=Set.newenddefignore_column(name)ignored_columns<<name.to_sendendend