Polymorphic controller and calling object

I have a polymorphic relationship with address being able to both be owned by a member or a dependent. Everything looked great until I realized that I wouldn't know what type of object was creating it unless I'm missing something. Is there a way to tell the routing file to include the type of object?

Models:

 class Member < ActiveRecord::Base
   has_one :address, as: :person, dependent: :destroy
 end

 class Dependent < ActiveRecord::Base
   has_one :address, as: :person, dependent: :destroy
 end

 class Address < ActiveRecord::Base
    belongs_to :person, polymorphic: true
 end

Controller:

 def new
  @person = ???
  @address = Address.new(person: @person)
 end

Routes Currently:

  resources :members do
    resources :addresses, shallow: true
    resources :dependents, shallow: true do
      resources :addresses, shallow: true
    end
  end

I have routes to address under each but would need to check for params[:member_id] or params[:dependent_id] I think. What happens when I attach notes to everything. I'm probably missing some easy way to do this in Rails, any advice would be greatly appreciated!

Basically you want to set the person object before creating a address. You can do this in your address controller like this:

In your Address controller:

class AddressesController < ApplicationController  
  before_action :set_person

  def new
    @address = @person.build_address
  end

  def set_person
    klass = [Member, Dependent].detect{|c| params["#{c.name.underscore}_id"]}
    @person= klass.find(params["#{klass.name.underscore}_id"])
  end
end

As for your routes file, currently according to the relationships that you have defined in your models the following should work:

resources :members do
 resource :address #singular resource routing as its a has_one relationship
end

resources :dependents do
  resource :address #singular resource routing as its a has_one relationship
end

(Notice that I have used singular routing for nested resource. You can read more on it here : http://guides.rubyonrails.org/routing.html#singular-resources)