recently I was trying to create a chatbot using dialogflow. I had setup and trained the dialogflow agent as intended. After this, I created a backend. Although, it was in its initial step for testing purposes. I was just making sure that the agent is hitting the backend or not. I created the backend using fast api. I tried by giving some input to the agent. Basically it is a food ordering chatbot. I am getting this error everytime when i gave order id.

Note: I created a tunnel via ngrok for https request.

I was testing a “track.order – context: ongoing-tracking” intent whether it is receiving the request or not in the backend. I just wanted to expect something like this when the user gave order id:

received ==track.order - ongoing-tracking== in the backend

But I am getting:

Default response: Not available

Also getting this fulfillment status in json response:

Webhook call failed. Error: Failed to parse webhook JSON response: Expect message object but got: null.

Fulfillment response:

{}

Fulfillment Request:

{
  "responseId": "5b7e5f8f-0f03-442d-b57b-6ecc96d49237-8d7c4bc4",
  "queryResult": {
    "queryText": "45",
    "parameters": {
      "order_id": 45
    },
    "allRequiredParamsPresent": true,
    "fulfillmentMessages": [
      {
        "text": {
          "text": [
            ""
          ]
        }
      }
    ],
    "outputContexts": [
      {
        "name": "projects/zara-restro-bot-9kaw/agent/sessions/410a07bb-14a7-1b4e-e0ec-207c145cef2a/contexts/ongoing-tracking",
        "lifespanCount": 1,
        "parameters": {
          "order_id": 45,
          "order_id.original": "45"
        }
      }
    ],
    "intent": {
      "name": "projects/zara-restro-bot-9kaw/agent/intents/caa8cbd8-a75a-48dd-aa61-92b050f15fc4",
      "displayName": "track.order - context: ongoing-tracking"
    },
    "intentDetectionConfidence": 1,
    "diagnosticInfo": {
      "webhook_latency_ms": 574
    },
    "languageCode": "en",
    "sentimentAnalysisResult": {
      "queryTextSentiment": {
        "score": 0.1,
        "magnitude": 0.1
      }
    }
  },
  "webhookStatus": {
    "code": 3,
    "message": "Webhook call failed. Error: Failed to parse webhook JSON response: Expect message object but got: null."
  }
}

Raw Api Response:

{
  "responseId": "5b7e5f8f-0f03-442d-b57b-6ecc96d49237-8d7c4bc4",
  "queryResult": {
    "queryText": "45",
    "parameters": {
      "order_id": 45
    },
    "allRequiredParamsPresent": true,
    "fulfillmentMessages": [
      {
        "text": {
          "text": [
            ""
          ]
        }
      }
    ],
    "outputContexts": [
      {
        "name": "projects/zara-restro-bot-9kaw/agent/sessions/410a07bb-14a7-1b4e-e0ec-207c145cef2a/contexts/ongoing-tracking",
        "lifespanCount": 1,
        "parameters": {
          "order_id": 45,
          "order_id.original": "45"
        }
      }
    ],
    "intent": {
      "name": "projects/zara-restro-bot-9kaw/agent/intents/caa8cbd8-a75a-48dd-aa61-92b050f15fc4",
      "displayName": "track.order - context: ongoing-tracking"
    },
    "intentDetectionConfidence": 1,
    "diagnosticInfo": {
      "webhook_latency_ms": 574
    },
    "languageCode": "en",
    "sentimentAnalysisResult": {
      "queryTextSentiment": {
        "score": 0.1,
        "magnitude": 0.1
      }
    }
  },
  "webhookStatus": {
    "code": 3,
    "message": "Webhook call failed. Error: Failed to parse webhook JSON response: Expect message object but got: null."
  }
}

My backend fast api code is:

from fastapi import FastAPI
from fastapi import Request
from fastapi.responses import JSONResponse

app = FastAPI()


@app.post("/")
async def handle_request(request: Request):
    payload = await request.json()

    intent = payload['queryResult']['intent']['displayName']
    parameters = payload['queryResult']['parameters']
    output_contexts = payload['queryResult']['outputContexts']

    if intent == "track.order - context: ongoing-tracking":
        return JSONResponse(content={
            "fulfillmentText": f"Received =={intent}== in the backend"
        })