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

Try this.. It will help....

index do
  column :city, :sortable => :"cities.name" do |district|
    district.city.human_name(:count => :other) if district.city.present?
  end
end

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

Answer 2

Very simple and readable solution:

index do
  column :city, sortable: "cities.name"
end

controller do
  def scoped_collection
    # join cities
    super.includes :city
  end
end

Answer 3

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

Answer 4

Use the name of the table, probably cities. It might look like this:

District.joins(:city).order("cities.name")