Forum: Ruby on Rails Polymorphic association question

This is an example from the geokit plugin which I am trying to
reproduce.

class Location < ActiveRecord::Base
  belongs_to :locatable, :polymorphic => true
  acts_as_mappable
end

class Company < ActiveRecord::Base
  has_one :location, :as => :locatable  # also works for belongs_to
associations
  acts_as_mappable :through => :location
end


We see two separate models here.  Now is there also a third model, like
some kind of join table?  Also is there a locatable_id:integer and
locatable_type:string as well?

The polymorphic :locatable association implies a :locatable_type and
:locatable_id column. These columns reference a row in an arbitrary 
table
identified by :locatable_type so no join table is needed.

On Feb 7, 2010 11:02 PM, "Sean Six" <lists@ruby-forum.com> wrote:

This is an example from the geokit plugin which I am trying to
reproduce.

class Location < ActiveRecord::Base
 belongs_to :locatable, :polymorphic => true
 acts_as_mappable
end

class Company < ActiveRecord::Base
 has_one :location, :as => :locatable  # also works for belongs_to
associations
 acts_as_mappable :through => :location
end


We see two separate models here.  Now is there also a third model, like
some kind of join table?  Also is there a locatable_id:integer and
locatable_type:string as well?
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