Listing, restricting attributes on Single Table Inheritance

Hi Gurus,

I am new to rails/ruby and have a simple question. I have single table
inheritence implemented for different equipment. Each equipment has some
common attributes such as equipment name, id, name of inspector etc…
but can have totally different attributes .

like base

create table equipments
( id autonumber |
type varchar |
comment varchar |
insepctor_id number |
insepction_date date |
Screen boolean > only for PC, TV
Keyboard boolean > Only for PC
Speaker boolean > Only for PC, hometheater
Remote boolean > Only for hometheater, TV
and so on …

So the heiracrhy is pretty simple i.e 2 levels , equipment is the base
class and particular type of equipments such as TV are derived classes

               Equipment - base class
        TV , hometheater, PC - derived classes of base class .

Here are my problems

  • How do i define the attributes for each type of Equipment such as TV ,
    PC , Hometheater in the model so that i can restrict the access to other

  • How can get i list of attributes which are applicable for that Class
    such as TV, PC or Hometheater?

I would like to write the generic forms, views ,controller for all the
classes using the tips in
. Are there are any examples ?

Thanks and I appreciate your Help,