Google Apps Script - Unable to query property from JSON data - json

Question

dialogflow sends the following:
{
"responseId": "XXX-YYY-ZZZ",
"queryResult": {
"queryText": "random text",
"parameters": {
"command": "do it"
},
"allRequiredParamsPresent": true,
"fulfillmentText": "Sorry, can't understand it.",
"fulfillmentMessages": [
{
"text": {
"text": [
"Sorry, can't understand it."
]
}
}
],
"outputContexts": [
{
"name": "projects/xxx-vyyy/agent/sessions/xxx-yyy-zzz/contexts/__system_counters__",
"parameters": {
"no-input": 0,
"no-match": 0,
"command": "do it",
"command.original": "do it"
}
}
],
"intent": {
"name": "projects/xxx-vyyy/agent/sessions/xxx-yyy-zzz",
"displayName": "testCommands"
},
"intentDetectionConfidence": 1,
"languageCode": "en"
},
"originalDetectIntentRequest": {
"payload": {}
},
"session": "projects/xxx-vyyy/agent/sessions/xxx-yyy-zzz"
}
TypeError: Cannot read property 'parameters' of undefined (line 5, file "this-file")
and the goal is to query the command field. This is the current code:
function doPost(e) {
//EXTRACTION
var dialogflow = e.postData.contents;
var desiredField = dialogflow.queryResult.parameters.command;
}
but then this error thrown:
TypeError: Cannot read property 'parameters' of undefined (line 4, file "this-file")
I tried JSON.stringify(e) and e.postData.contents, but still not working.
Documentation on doPost() https://developers.google.com/apps-script/guides/web
and WebhookRequest sent by dialogflow https://cloud.google.com/dialogflow/docs/fulfillment-webhook#webhook_request
Thanks in advance!

Answer 1

At doPost(e), e.postData.contents is not parsed as JSON object. I think that your error message is due to this. So how about the following modification using JSON.parse()?
Modified script:
function doPost(e) {
//EXTRACTION
var dialogflow = JSON.parse(e.postData.contents); // Modified
var desiredField = dialogflow.queryResult.parameters.command;
}
Reference:
Web Apps