"bills".* FROM "bills" ORDER BY bills.date DESC LIMIT 1 => #<Bill id: 15, name: "123", description: "45", user_id: 9, date: "2013-06-12 00:00:00", value: #<BigDecimal:43384f8,'0.124E3',9(36)>, created_at: "2013-06-19 01:17:36", updated_at: "2013- 06-19 01:17:36"> irb(main):009:0> comment_2 = Comment.new :content => "Comentário de uma conta" => #<Comment id: nil, content: "Comentário de uma conta", created_at: nil, updated_at: nil, commentable_id: nil, commentable_type: nil> irb(main):011:0> comment_2.commentable = bill => #<Bill id: 15, name: "123", description: "45", user_id: 9, date: "2013-06-12 00:00:00", value: #<BigDecimal:41fbae0,'0.124E3',9(36)>, created_at: "2013-06-19 01:17:36", updated_at: "2013- 06-19 01:17:36"> irb(main):012:0> comment_2.save (0.1ms) begin transaction SQL (0.7ms) INSERT INTO "comments" ("commentable_id", "commentable_type", "content", "created_at", "updated_at") VALUES (?, ?, ?, ?, ?) [["commentable_id", 15], ["commentable_type", "Bill"], ["content", "Comentário de uma conta"], ["created_at", Tue, 25 Jun 2013 17:44:17 UTC +00:00], ["updated_at", Tue, 25 Jun 2013 17:44:17 UTC +00:00]] (430.8ms) commit transaction => true irb(main):013:0> bill.comments Comment Load (0.4ms) SELECT "comments".* FROM "comments" WHERE "comments"." commentable_id" = 15 AND "comments"."commentable_type" = 'Bill' ORDER BY comments. created_at DESC => [#<Comment id: 3, content: "Comentário de uma conta", created_at: "2013-06-25 17:44:17", updated_at: "2013-06-25 17:44:17", commentable_id: 15, commentable_type: "Bill">]