title: Jmeter - get nested Json string
body: <p>I'm using Jmeter for API test. in one of the responses I get Json that includes the same key ("id") twice - nested and not.
  this is an example of the response (part of it):</p>
  
  <pre><code>{
  "id": "3600f05a-2ef6-490d-95af-7742f652cbfd",
  "progress": 1,
  "status": "done",
  "task_update_time": "2016-01-24T08:23:12.274Z",
  "result": {
    "id": "c8b1ed07-0b57-4473-a4d7-08f7b829aad7",
    "name": "testPrintFlow",
    "geom": {
  </code></pre>
  
  <p>now, I want to get the second (nested) "id". until now I used Regular expression extractor. I can use it also in this case, like this:</p>
  
  <pre><code>"result":{"id":"(.+?)"
  </code></pre>
  
  <p>but I want something more robust. I guess I can use some Json library, but I made few tries and there seem to be many holes. can someone please recommend (and explain) what is the best way? either regular expression or Json. Thanks.</p>