gistfile1.txt

POSTing this JSON document to /configurations:

{
  "name":                       "lacquered",
  "notes":                      "...",
  "parent_configuration_href":  "http://config.ssbe.localhost/configurations/90"
}

parent_configuration_href references another configuration in this application. 
Our URIs are opaque, so href is the only a client is allowed to reference it. 
I'd like to de-munge this into a "parent_id" in params:

{"configuration"=>{"name"=>"lacquered", 
                   "notes"=>"...", 
                   "parent_id"=>90}, 
"format"=>nil, "action"=>"create", "controller"=>"configurations"}