Implementation of ActiveAdmin::PunditAdapter and usage of Pundit with ActiveAdmin. A PR is opened here : https://github.com/gregbell/active_admin/pull/2857

comment_policy.rb

# app/policies/active_admin/
module ActiveAdmin
  class CommentPolicy < ApplicationPolicy
    class Scope < Struct.new(:user, :scope)
      def resolve
        scope
      end
    end
  end
end

page_policy.rb

# app/policies/active_admin/
module ActiveAdmin
  class PagePolicy < ApplicationPolicy
    class Scope < Struct.new(:user, :scope)
      def resolve
        scope
      end
    end

    def show?
      case record.name
      when 'Dashboard'
        user.admin?
      else
        false
      end
    end
  end
end

pundit_adapter.rb

# in lib/active_admin/
require 'pundit'

# https://github.com/gregbell/active_admin/blob/master/lib/active_admin/authorization_adapter.rb
module ActiveAdmin
  # References 
  #
  # Default Authorization permissions for Active Admin
  #
  # module Authorization
  #   READ    = :read
  #   CREATE  = :create
  #   UPDATE  = :update
  #   DESTROY = :destroy
  # end
    
  class PunditAdapter < AuthorizationAdapter
    def authorized?(action, subject = nil)
      action = if subject.is_a? Class 
        :index?
      else
        override_action_name action
      end
      Pundit.policy(user, subject).public_send action
    end

    def scope_collection(collection, action = Auth::READ)
      Pundit.policy_scope(user, collection)
    end

    def override_action_name(action)
      case action
      # https://github.com/elabs/pundit/blob/master/lib/generators/pundit/install/templates/application_policy.rb
      when :read
        :show?
      when :create
        :create?
      when :update
        :update?
      when :destroy?
        :destroy?
      else
        "#{ action }?"
      end
    end
  end
end

A PR is opened here : activeadmin/activeadmin#2857

very nice!

I followed this to setup active admin to pundit authorization, but on the page_policy.rb the user instance is nill instead of getting the current logged in user

This plugin allowed the login page to show but when I used the [email protected] and password credentials I got Pundit::AuthorizationNotPerformedError in Admin::DashboardController#index this error. How do I authorize the rest of AA at this point?

I ran into a similar issue.

undefined methodread' for #ActiveAdmin::PagePolicy:0x007ffa06cc1598`

I am also getting Pundit::AuthorizationNotPerformedError in Admin::DashboardController#index error when accessing the dashboard

I was able to solve the Pundit::AuthorizationNotPerformedError in Admin::DashboardController#index by using the following in my app/admin/dashboard.rb:

ActiveAdmin.register_page "Dashboard" do
  controller do
    before_filter :authorize_index, only: :index
    def authorize_index
      policy_scope(User)
    end
  end
  menu priority: 1, label: proc{ I18n.t("active_admin.dashboard") }

  content title: proc{ I18n.t("active_admin.dashboard") } do
    div class: "blank_slate_container", id: "dashboard_default_message" do
      span class: "blank_slate" do
        span I18n.t("active_admin.dashboard_welcome.welcome")
        small I18n.t("active_admin.dashboard_welcome.call_to_action")
      end
    end
end

See this SO solution for more info and explination: http://stackoverflow.com/a/34980939/511168