Adding methods to ActiveRecord::Relation to wrap results

gistfile1.rb

require "spec_helper"

class RecordWrapper
  def initialize(record)
    @record = record
  end
end

module RelationWrapping

  def self.included(mod)
    mod.class_eval do
      attr_accessor :wrap_with_class
      alias_method_chain :to_a, :wrapper
    end
  end

  def wrap_results_with(klass)
    relation = clone
    relation.wrap_with_class = klass
    relation
  end

  def to_a_with_wrapper
    if not loaded? and wrap_with_class
      @records = to_a_without_wrapper.collect{ |record| wrap_with_class.new(record) }
    else
      to_a_without_wrapper
    end
  end

end

ActiveRecord::Relation.send(:include, RelationWrapping)

class ActiveRecord::Base
  class << self
    delegate :wrap_results_with, :to => :scoped
  end
end

describe "RelationWrapping" do

  it "wraps records" do
    users = User.wrap_results_with(RecordWrapper).limit(5)
    users.all?{ |user| user.instance_of?(RecordWrapper) }.should be_true
  end

end