Comments belonging to two different models

Hello,
I am building a project management application, and I want my clients
to be able to comment on multiple things.
For instance I have 2 models: milestones, and tickets, I have the
foreign keys for both of them in the comments model and linked them
with has_many and belongs_to. I am just wondering if this is possible?
Or if there is a better way to do it.

Thanks,
Ben.

What you really need is polymorphic associations.

But you can also just get a plugin with the code already implemented -
http://github.com/jackdempsey/acts_as_commentable/tree/master