# 1 comment system for multiple models **URL:** \ **Category:** Rails\ **Created:** [September 19, 2008, 2:36pm UTC](https://www.ruby-forum.com/t/1-comment-system-for-multiple-models/149026 "2008-09-19T14:36:44Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Tarscher](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/8491ac/32.png) [@Tarscher](https://www.ruby-forum.com/u/Tarscher)\ **Post date:** [September 19, 2008, 2:36pm UTC](https://www.ruby-forum.com/t/1-comment-system-for-multiple-models/149026/1 "2008-09-19T14:36:44Z")
Hi all, I have a commenting system I use on different models (posts, reports, events) meaning that I have some difficulties using depend =\> destroy and counter cache. I now use a sub\_id in my comment indicating whether the comment belongs to a post, event or report eg: Events table id | owner\_id | category\_id | text 0 1 post … 1 1 event … 2 2 report … 3 2 post … Where the owner\_id is the id own the post, event or report. This approach makes it hard to use either counter cache or depend =\> destroy since it will only look at the owner\_id. If a user deletes post 1 it will also delete the comments of both event 1 and report 1. Someone has a better approach to using 1 comment system for multiple models or can I overwrite counter cache and depend destoy to make use of scoping? All help is greatly appreciated. Stijn ---
**Author:** ![Tarscher](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/8491ac/32.png) [@Tarscher](https://www.ruby-forum.com/u/Tarscher)\ **Post date:** [September 19, 2008, 3:06pm UTC](https://www.ruby-forum.com/t/1-comment-system-for-multiple-models/149026/2 "2008-09-19T15:06:48Z")
What you want to use here are polymorphic associations. They work mostly like what you have done, using two columns, one for the id, the other for the type. commentable\_id commentable\_type in your case. Then you could define associations like has\_many :comments, :as =\> :commentable, :dependent =\> :destroy and Rails would be able to handle al the sub tasks as it does with common associations. read the details here: > **[ActiveRecord::Associations::ClassMethods](https://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html)** > > Associations are a set of macro-like class methods for tying objects together through foreign keys. since it’s a bit too complex to explain it here