1 comment system for multiple models

rubyonrails-talk
1

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

2

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:

since it's a bit too complex to explain it here