Property transfer using JSON nodes count

How to perform property transfer to keep track on no of nodes returned in JSON response:

eg:

{
     "firstName": "John",
     "lastName" : "doe",
     "age"      : 26,
     "address"  :
     {
         "streetAddress": "naist street",
         "city"         : "Nara",
         "postalCode"   : "630-0192"
     },
     "phoneNumbers":
     [
         {
           "type"  : "iPhone",
           "number": "0123-4567-8888"
         },
         {
           "type"  : "home",
           "number": "0123-4567-8910"
         }
     ]
 }

here for phoneNumbers we have 2 nodes.