controller

class RolesController < ApplicationController
  include Hydra::RoleManagement::RolesBehavior

  prepend_before_filter :accept_batches, only: [:destroy]

  def destroy
    @roles.each {|role| role.destroy}
    redirect_to roles_path, notice: "Successfully deleted groups: #{params[:ids].join(", ")}"
  end

  def accept_batches
    if params[:id]
      params[:ids] = [params[:id]].flatten
      params[:id] = nil
    end
    params[:ids] ||= []

    #This implementation of batch works based upon cancan's returning of all roles when no params[:id] is supplied
    #Thus authorize_resource is checking can? :delete, Role instead of can? :delete, 1, can? :delete, 2, etc.
    #Or is cancan able to check @roles instead?!?
    @roles = Role.where(id: params[:ids])
  end
end

routes snippet

resources :roles do
  collection do
    delete :destroy
  end
end