how would you refactor this to make it more DRY

i have your typical nested resource pattern, and at most any resource
is one level deep... so for a model PurchaseOrder which is optionally
nested under Customer ive worked up this before_filter...

but the problem is, i have my parent class name hard coded into the
function... so i can either copy this to every controller (which i
really know in my heart cant be appropriate) or ask for some input...

now i know all about resource_controller and the make_resourceful
plugins... but they're all a bit too magical and over the top for my
needs - as awesome as they may be.

anyhow... heres the function.

  def load_parent
    class_name = :customer
    parent_sym = "#{class_name.to_s}_id".to_sym
    parent_class = class_name.to_s.classify.constantize

    # if there is a customer_id in params then load it...
    #if not return the current controllers class, constantized so i
can do things like
    # @purchase_order = @parent.find(params[:id])
    # in my actions and have it work regardless of the presence of a
parent or not.

    @parent = params[parent_sym] ?
(self.controller_name.tableize.to_sym) :