I have three models where a basiccase has a form. Basic case can create a new form.

class User < ActiveRecord::Base
  has_many :basiccases
end

class Basiccase < ActiveRecord::Base
  belongs_to :user
  has_one :basiccases      
end

class Form3C < ActiveRecord::Base
 belongs_to :basiccases
end

I want to create an instance of form 3c in the form3c controller. Can any one explain me how I can carry the basiccase_id to the form3c controller to set the foreign key attribute. I can set the value using @basiccase.build_form3_c but I'm not sure how I can get the basiccase_id from the basiccase.