Active Admin Version Panel

activeadmin.rb

# lib/ext/activeadmin.rb
module ActiveAdminPaperTrailDetails
  def versions
    panel 'Versions', class: 'versions' do
      table_for resource.versions.order :created_at do
        column(:whodunnit) { |v| auto_link User.find_by(id: v.whodunnit) }
        column :event
        column 'When', :created_at
        column 'Changes' do |v|
          attributes_table_for v.changeset.to_a do
            row(:attribute) { |attr, _| attr }
            row(:before)    { |_, (before, _)| before }
            row(:after)     { |_, (_, after)| after }
          end
        end
      end
    end
  end
end