Using scaffolding with Ruby 4.1.0 on existing Db

Thanks in advance for the great responses on this forum.

My question is this:

       Let's say I have a MySQL database with three tables. Referential
integrity is set up in the database, so invalid keys will cause a non
zero query return code.
       The tables are:
             Category which owns table Type and
             Type which owns table Widget and
             Widget which has description, price and quantity values.

       I want to generate a basic CRUD functionality over these three.
       I also want to have drop down boxes on Type and Widget so that
       Category parent can be selected for Type and
       Type parent can be selected for Widget

       What Ruby scaffolding commands would now be required to generate
and also deploy this?

       Is the Nifty gem the most complete, or are there now better

       There seems to have been changes since Ruby 2.0 previously
discussed on this forum. Yes?

       RoR is the best thing since sliced bread!