How to implement ancestry for this specific situation

Question

We have a Real-Estate app in which the User can be a Renter or Landlord(Owner). Renters can search for specific houses listed by the Owners. Renters can also add other persons(friends or acquaintances who are staying with that specific renter). In the app we treat them as Coapplicants.

Models

# user.rb
class User < ActiveRecord::Base
  has_one :renter
  has_one :owner
end

# renter.rb
class Renter < ActiveRecord::Base
  belongs_to :user
  has_many :coapplicants
end

# coapplicant.rb
class Coapplicant < ActiveRecord::Base
  belongs_to :renter
end

Now as to increase the number of users for the app,we implemented a mailing system which sends an Welcome Mail(when the Renter adds a Coapplicant) to signup as a User.And that Coapplicant can choose to be Renter and can add many Coapplicants too. And the process goes on again resulting in increasing the users.

It's like a tree structure and now I want to set-up a perfect database relations(associations) to track the users flowing in and through which renter/coapplicant they are coming.

Now the Current Model structure(not yet developed) looks like this

# user.rb
class User < ActiveRecord::Base
  has_one :renter
  has_one :owner
end

# renter.rb
class Renter < ActiveRecord::Base
  belongs_to :user
  has_many :coapplicants
  has_many :coapp_renters,
           :through => :coapplicants
  has_many :inverse_coapplicants,
           :class_name => "Coapplicant",
           :foreign_key => "coapp_renter_id"
  has_many :inverse_coapp_renters,
           :through => :inverse_coapplicants,
           :source => :renter
end

# coapplicant.rb
class Coapplicant < ActiveRecord::Base
  belongs_to :renter
  belongs_to :coapp_renter,
             :class_name => "Renter"
end

I guess i messed up things a bit. Which database-relationships(associations) would be the best for my current situation.

Can someone throw some light on this please.I'm thinking about using the ancestry gem but how to implement to my current situation.

Answer 1

I would refactor your code and make the co-applicants just a renter that is a child of another renter

in your renter model you have to add a "parent_id" to know whom the co-applicants belongs to.

now in your model you can do something like

#renter.rb
class Renter < ActiveRecord::Base
  belongs_to :user
  has_many :children, :class_name => "Renter"
  belongs_to :parent, :class_name => "Renter" 
end

# Example calls 
Renter.first.children 
Renter.first.parent 

I hope this helps