aws lex v2 dynamic fulfillment from backend - node.js

Question

Context
I'm using aws lex V2 and I have already set up a flow so that the user can make an appointment. The thing is that I would like to return (dynamic values) to the user something like:
Expected result
use dynamic values from the backend
ex:
Your appointment has been confirmed. Please keep the following code: {{appointment_code}} when you show up to the interview.
Actual Result
ex:
Your appointment has been confirmed.
When you set up the fulfillment output in aws lex v2, you defined the "static" content of the response, or add the value of the slots using {slotName} in the sentence. No matter what a set my message content from my backend response. i always get the response configure from the aws lex console, but not from the backend.
some code
The response that I'm using after i get all the necessary slots and generate the appointment "code reference" is the following:
function close(sessionAttributes, message) {
return {
"sessionState":{
sessionAttributes,
"dialogAction": {
"type": 'Close',
},
"intent": {
"name": "PetitionsIntent",
"state": "Fulfilled"
},
"messages": [
{
"contentType": "PlainText",
"content": `cool, the apointment code is ${ap_code}`,
}
],
}
};
}
The code works and the intent is fulfilled, but I get the response from the pre-defined lex console(image above) and not from the backend response.
Is there a way to overwrite the predefined output and use the lambda response instead?
What am I missing?

Answer 1

It would appear that your Lambda function has not been invoked.
Clicking the Advanced options button under your fulfillment message will slide in a menu from the right.
Ensure that you've checked the Use a Lambda function for fulfillment option under the Fulfillment Lambda code hook heading.
This assumes that you have correctly configured your bot to make use of a Lambda function.
Also note that Lex will use a different value for invocationSource to denote that all slots have been fulfilled. So your Lambda function will need to look out for FulfillmentCodeHook instead of DialogCodeHook.