PaperTrail ActiveAdmin history pane

app_admin_resourcename.rb

ActiveAdmin.register DeviceState do
  # ...
  action_item :history, only: :show do
    link_to 'History', [:history, :admin, resource]
  end
  member_action :history do
    render "layouts/history"
  end
  # ...
end

app_views_layouts_history.html.arb

panel "History" do
  table_for resource.versions do
    column "At", &:created_at
    column "Action", &:event
    column "By" do |v|
      user = User.find_by(id: v.whodunnit)
      if user
        auto_link(user)
      else
        span "nobody"
      end
    end
    column "" do |v|
      if v.changeset.empty?
      else
        table style: 'margin: 0' do
          thead do
            tr do
              th "Changed"
              th "From"
              th "To"
            end
          end
          tbody do
            v.changeset.each do |(field_name, c)|
              next unless field_name != 'updated_at'
              tr do
                td field_name
                td c.first
                td c.last
              end
            end
          end
        end
      end
    end
  end
end

cancan_ability

# If using CanCan. Use a similar thing to authorize the "history" action if using Pundit for example.

# ...
        can %i[read history], ResourceName
# ...