SUMMARY: How do I assign objects, of different subclasses of an abstract class, to a belongs_to relation?
I had the following class hierarchy:
Location < ActiveRecord::Base Address < Location Building < Location
and a class Person with these relationships: has_one :address, :dependent => :destroy belongs_to :building
Location is backed by table "locations," and Person by "People."
I had to refactor to insert an abstract class between Location and Building:
Location < ActiveRecord::Base Address < Location SharedLocation < Location Building < SharedLocation DeletedLocation < SharedLocation
I now want Person#building to refer to either a Building or a DeletedLocation. Refactoring the foreign key and accessor would be a major pain.
I changed the relation for Person#building to: belongs_to :building, :class_name => 'SharedLocation', :foreign_key => 'building_id'
(:foreign_key because I got a deprecation warning on specifying :class_name without one.)
I also moved has_many :people, :dependent => :nullify from Building to SharedLocation. In the course of flailing about for a solution, I added ":foreign_key => 'building_id'", but I don't know what I'm doing.
I ran my unit tests for setting the relation, and am now seeing failures/errors, all of which seem to boil down to this: Attempting person = Building.new(...) gets an AssociationTypeMismatch, "SharedLocation expected, got Building."
How do I make belongs_to relations polymorphic?
Rails 2.3.2 ruby 1.8.7 (2008-08-11 patchlevel 72) [universal-darwin10.0]