[Catalyst] Custom fields in a model

[Greg Coates]

I have a database table -- let's call it 'Contacts' that I'm accessing 
through a DBIx::Class model.  This table has two fields called 
'first_name' and 'last_name'.

Could I get some suggestion on the best way to add code to the model (or 
the schema) to allow me to add a custom field to the resultset without 
having an actual column in the database table?  I want to be able to 
access a field in the resultset called something like 'common_name'. 
This field would contain a concatenation of the first and last name 
fields for people and only the data from the last name for other 
entities like businesses.

Thanks!

Greg Coates