optional belongs_to for renamed active_admin resources

Question

if belongs_to is optional url helpers are created with use of polymorphic_path and polymorphic_link methods. This methods don't know anything about resource renaming in active admin.

How can I use optional belongs_to for renamed resource pages

backtrace:

ActionView::Template::Error (undefined method `new_admin_region_country_region_city_path' for #<Admin::CitiesController:0x00000006bb1dd0>):
1: insert_tag renderer_for(:index)
  actionpack (4.0.9) lib/action_dispatch/routing/polymorphic_routes.rb:129:in `polymorphic_url'
  actionpack (4.0.9) lib/action_dispatch/routing/polymorphic_routes.rb:147:in `new_polymorphic_path'
  inherited_resources (1.5.1) lib/inherited_resources/url_helpers.rb:222:in `new_resource_path'
  actionpack (4.0.9) lib/abstract_controller/helpers.rb:53:in `new_resource_path'
  arbre (1.0.2) lib/arbre/element.rb:180:in `method_missing'
  /home/senid/.rvm/gems/ruby-2.1.2@belongs_to/bundler/gems/active_admin-a2cd9604c2d9/lib/active_admin/resource/action_items.rb:61:in `block in add_default_action_items'
  /home/senid/.rvm/gems/ruby-2.1.2@belongs_to/bundler/gems/active_admin-a2cd9604c2d9/lib/active_admin/views/action_items.rb:9:in `instance_exec'
  /home/senid/.rvm/gems/ruby-2.1.2@belongs_to/bundler/gems/active_admin-a2cd9604c2d9/lib/active_admin/views/action_items.rb:9:in `block (2 levels) in build'

app/admin/region_city.rb

ActiveAdmin.register RegionCity, as: 'City' do
  permit_params :name, :description, :country_id
  menu false
  belongs_to :country, parent_class: RegionCountry, optional: true
  navigation_menu :default
  filter :id_eq
end

app/admin/region_country.rb

ActiveAdmin.register RegionCountry, as: 'Country' do
  permit_params :name, :description

  filter :id_eq

  sidebar 'Links', only: [:show] do
    ul do
      li do
        link_to 'Cities', admin_country_cities_path(country_id: resource.id)
      end
    end
  end

end

app/models/region_city.rb

class RegionCity < ActiveRecord::Base
  belongs_to :country, class_name: RegionCountry, foreign_key: :country_id
  validates :name, presence: true
  validates :country, presence: true
end

app/models/region_country.rb

class RegionCountry < ActiveRecord::Base
  validates :name, presence: true
  has_many :cities, class_name: RegionCity, foreign_key: :country_id
end

Gemfile.lock

GIT
  remote: git://github.com/gregbell/active_admin.git
  revision: a2cd9604c2d949f5193791045385756cee0c6865

small test app that repeats an error:

https://github.com/senid231/activeadmin_test_belongs_to

Answer 1

ActiveAdmin allows you to use nested resources with a belongs_to method, as you clearly already know:

ActiveAdmin.register Project do 
end

ActiveAdmin.register Ticket do
  belongs_to :project
end

ActiveAdmin.register Milestone do 
  belongs_to :project
end

Because Inherited Resources' firepower can't be aware of every custom implementation in the book, you may have to explicitly tell your ActiveAdmin controller how to access the child resources from the parent resource. So, your child classes would end up looking something like this:

ActiveAdmin.register RegionCity, as: 'City' do
  belongs_to :country
  ...snipped....

  controller do 
    defaults :collection_name => "region_cities"
  end
end

Because ActiveAdmin uses Inherited Resources as its source of power, any additional tweaking you may need in addition to my help will be found in the Inherited Resources documentation. This sort of example in specific is in the Overwriting Defaults section. IR isn't currently being maintained, so don't be surprised by all the Rails 3 references.

Hope this helps!