Subclasses - help required


I dealt with a similar problem recently and ended up creating one AR
table with a series of boolean flags to indicate if the object was a
member of a particular child class. Just like your example I wanted
the ability for child objects from different classes to inherit from
a single parent class.

Here is a rough idea of what I did:

class Staff < ActiveRecod::Base
   # connected to the one table where all data is stored
   # add one boolean column for each subclass

class Manager < Staff
   def initialize(attributes = nil)
     # set is_manager to true for all new objects
     super(:is_manager => true)
     self.attributes = attributes unless attributes.nil?

   class << self
     def find(*args)
       self.with_scope(:find => {:conditions =>
["staff.is_manager=?",true]}) do

Then just repeat the above for your engineer and producer classes.
There are some problems with this approach. The rails paginator
still counts the number of records in the base class. I think this
can be solved by overriding the method that determines the number of
records. Another problem is that the scoped find does not catch
calls to the various find convenience methods that rails provides.

I am very interested to hear how other people have solved this problem.