ActiveRecord validations, uniquness conditioning

in ActiveRecord::Base validations Select multiple columns in uniquness and
Also, is it possible to add the value of the column to the conditions?

What do you want to be uniquness?
- user_id
- mst_category_id
- In addition, active=true

I thought it was like this, but it was completely different...

class User<ActiveRecord::Base

values:user_id,
unity: {
scope:[:mst_category_id, active:true]
}