Example Dialogflow CX webhook as Node JS cloud function

index.js

const functions = require('@google-cloud/functions-framework');

// Here's where you set the entry point, it gets the request from Dialogflow CX 
// and it holds the response which will be sent back to Dialogflow 
functions.http('orderState', (req, res) => {
    let msg;
    let results = {};
    //let item;
  
    //Let's log whatever we receive from Dialogflow CX to understand things better
    console.log(req.body);

    if(req.body.sessionInfo && req.body.sessionInfo.parameters){
        // params will hold all the Dialogflow CX session parameters
        let params = req.body.sessionInfo.parameters;

      	// For example, I can fetch an item name
        //if(params.item) {
        //  item = params.item;	
        //}
    }

    if(req.body.fulfillmentInfo && req.body.fulfillmentInfo.tag){
        let tag = req.body.fulfillmentInfo.tag;

        switch (tag) {
            case 'add':
                let addResults = getAddToOrder(params);
                msg = addResults.msg;
                break;
            case 'update':
                let updateResults = getUpdateOrder(params);
                msg = updateResults.msg;
                break;         
            case 'remove':
                let removeResults = getRemoveFromOrder(params);
                msg = removeResults.msg;
                break;         

            default:
              let results = {
                "success": false
              }
              msg = "Something went wrong. Please try again.";
        }
        
    }

    // Build and return the response.
    const response = {
        fulfillmentResponse: {
        messages: [
            {
                text: {
                    text: [
                        msg // this is the message for the agent to return
                    ],
                },
            },
        ],
        },
        sessionInfo: {
            parameters: results, // these are the parameters that will be set and returned to the agent
        },
    };

    res.status(200).json(response);
});


function getAddToOrder(params){
  // TODO do something with "item"


  // set new parameters to the DFCX session
  let results = {
    "success": true,
    "action": "add",
    "orderId": "01222023"
  }
  results.msg = "Got it. I've added it to the order.";

  return results;
}

function getUpdateOrder(params){
  // TODO do something with "item"


  // set new parameters to the DFCX session
  let results = {
    "success": true,
    "action": "update",
    "orderId": "01222023"
  }
  results.msg = "Got it. I've updated the order.";

  return results;
}

function getRemoveFromOrder(params){
  // TODO do something with "item"


  // set new parameters to the DFCX session
  let results = {
    "success": true,
    "action": "remove",
    "orderId": "01222023"
  }
  results.msg = "Got it. I've removed it from your order.";

  return results;
}