Json value is returned with value noneType causing the code to fail. How does one make it more robust

Question

I have the following JSON which i am getting using REST API

looks something like this

"itineraryIntent": {
    "itineraryId": 2446,
    "userNodes": [
      {
        "user": {
          "id": "-2",
          "givenName": "Wiliam Never",
          "preferredAirport": "",
          "travelerGroupId": null,
          "externalId": null,
          "externalId2": null,
          "checkCCFieldForTraveler": false,
          "notificationEmailOverride": null,
          "paxType": 0,
          "title": "Dr",
          "middleName": null,
          "dateOfBirth": "1980-01-15T00:00:00Z",
          "phoneNumber": null,
          "tsaInfo": null,
          "source": "RequestEndPoint",
          "allowBookingGuestTraveler": null,
          "gdsTravelerProfileContainsFirstName": false,
          "profilesFound": {
            "Agency": null,
            "Corporate": null,
            "Traveler": null
          },
          "userId": "-2",
          "firstName": "Wiliam",
          "lastName": "Never"
        },
        "elements": []

I am using the following to get the information that i need

details = response.json()
checkIntent = details["itineraryIntent"]["userNodes"][0]["elements"]

if len(checkIntent) == 0:
  print("No intent found, nothing is classified")
       return False
else:
       return True

This code works 80% of the time. The problem is that sometimes i get

TypeError: 'NoneType' object is not subscriptable

What i have noticed is that when trying to get the response sometimes details["itineraryIntent"]["userNodes"] itself is null. I have tried to use isIntances and other methods but none of them work for me.

Currently i have implemented sleep for 10 seconds before getting the response, but that is not a good solution, cause most of the cases the proper response comes within 4-5 seconds.

How do i make this robust enough so that I can get the desired results without sleep.

Answer 1

details = response.json()         
if not details["itineraryIntent"]:             
   time.sleep(7)             
   response2 = requests.request("GET", url, headers=headers, data=payload)             
   details2 = response2.json()             
   checkIntent = details2["itineraryIntent"]["userNodes"][0]["elements"]         
else:             
   checkIntent = details["itineraryIntent"]["userNodes"][0]["elements"]         
   if len(checkIntent) == 0:             
      print("No intent found, nothing is classified")             
      return False         
   else:              
      return True