Rails 4: Show List of Items in third level associations

Question

I have Following structure in my rails app.

class Country < ActiveRecord::Base
  has_many :states
end

class State < ActiveRecord::Base
  has_many :cities
  belongs_to :country
end

class City < ActiveRecord::Base
  belongs_to :state
end

I want to access to cities from the country model. eg @country.cities . Also, how can I get the country from city model? eg @city.country

Thanks,

Answer 1

Use through option in has_many and delegate for belongs_to:

class Country < ActiveRecord::Base
  has_many :states
  has_many :cities, through: :states
end

class State < ActiveRecord::Base
  has_many :cities
  belongs_to :country
end

class City < ActiveRecord::Base
  belongs_to :state
  delegate :country, to: :state
end