module ActiveAdmin::DisplayHelper

def display_name_method_for(resource)

If no methods are available and we're about to use the Kernel's `to_s`, provide our own.
To prevent conflicts, we exclude any methods that happen to be associations.
Looks up and caches the first available display name method. 
def display_name_method_for(resource)
  @@display_name_methods_cache ||= {}
  @@display_name_methods_cache[resource.class] ||= begin
    methods = active_admin_application.display_name_methods - association_methods_for(resource)
    method = methods.detect { |method| resource.respond_to? method }
    if method != :to_s || resource.method(method).source_location
      method
    else
      DISPLAY_NAME_FALLBACK
    end
  end
end