cancan.rb

def index
  contacts_cancan = Contact.accessible_by(current_ability)

  respond_to do |format|
    format.html # index.html.erb
    format.json { render json: ContactsDatatable.new(view_context, contacts_cancan) }
  end
  
end

class ContactsDatatable
  delegate :params, :h, :link_to, :number_to_currency, to: :@view

  def initialize(view, contacts_cancan)
    @view = view
    @contacts_cancan = contacts_cancan
  end


  def fetch_contacts
    contacts = @contacts_cancan.order("#{sort_column} #{sort_direction}")
    contacts = contacts.page(page).per_page(per_page)
  end
end