ActiveAdmin rails-settings-cached

preference.rb

ActiveAdmin.register_page "Preference" do
  menu priority: 2
  content do

    form :action => admin_preference_update_path, :method => :post do |f|
      f.input :name => 'authenticity_token', :type => :hidden, :value => form_authenticity_token.to_s
      panel "Preference" do
        fieldset do
          ol do
            li do
              label 'dfg'
              f.input :name => "data[dfg]", :type => 'text', :value => Preference.dfg
            end
            li do
              label 'ddd'
              f.textarea :name => "data[ddd]" do
                Preference.ddd
              end
            end
          end
        end
      end
      f.input :type => 'submit', :value => 'Add'
    end
  end

  page_action :update, :method => :post do
    params['data'].each do |k, v|
      Preference[k] = v
    end
    redirect_to :back, :notice => "#{params[:key]} added"
  end
end