comment_threads and root_comments do not work with model inheritance

[stanguy]

If my commentable model has inherited models, using comment_threads or root_comments does not work as expected.

Steps to reproduce:

% rails new aacwt
[ cd aacwt, edit Gemfile, run bundle ]
% rails generate acts_as_commentable_with_threading_migration
% rails g model Post
% rails g model Article --parent=Post
% rails g model User
% rake db:migrate

> a = Article.create
> u = User.create
> c = Comment.build_from( a, u, "hello, world" )
> c.save
>  a.root_comments
 => [] # What!?

sqlite> select * from comments ;
1|1|Article||hello, world||1||1|2|2010-11-17 12:27:40.157701|2010-11-17 12:27:40.157701

Here, we have an Article as commentable_type.

% tail -1 log/development.log 
  Comment Load (0.2ms)  SELECT "comments".* FROM "comments" WHERE ("comments".commentable_id = 1 AND "comments".commentable_type = 'Post') AND ("comments"."parent_id" IS NULL) ORDER BY created_at ASC

But it looks for a Post commentable_type.

[ChristianPeters]

Well... I guess that's more or less a Ruby / Rails issue. But maybe elight can provide a workaround?

We did the following...

 @commentable = ConfigurableProduct.find(params[:commentable_id])
 # A dummy with the STI base class of the commentable is necessary
 # as the base class is expected when reading from the comments table
 dummy_commentable = @commentable.class.base_class.new
 dummy_commentable.id = @commentable.id

@comment = Comment.build_from(dummy_commentable,
                             current_user.id,
                             params[:comment][:body])

There is also a Rails method becomes which basically does the same: casting an object to the base class by creating a duplicate. However, we had huge problems with that because that screwed up all Product instances in the app when posting a comment (and executing becomes on one ConfigurableProduct).

[elight]

Yup. Fixed with 9737770 from arjun810.