ActiveAdmin: sort by child association's property

Question

I am having these objects:

class District < ActiveRecord::Base
  belongs_to :city
end
class City < ActiveRecord::Base
  has_many :districts
end
         


        

Answer 1

That should also do the work:

index do
  column City.model_name.human, :city, :sortable => 'cities.name'
end

controller do
  def scoped_collection
    end_of_association_chain.includes(:city)
  end
end