Cloud Function for Dialogflow BigQuery Integration

index.js

/**
 * Copyright 2017 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

'use strict';

const functions = require('firebase-functions');
const {google} = require('googleapis');
const {WebhookClient} = require('dialogflow-fulfillment');
const BIGQUERY = require('@google-cloud/bigquery');


// Enter your calendar ID below and service account JSON below
const calendarId = "[email protected]";
const serviceAccount = {}; // Starts with {"type": "service_account",...

// Set up Google Calendar Service account credentials
const serviceAccountAuth = new google.auth.JWT({
  email: serviceAccount.client_email,
  key: serviceAccount.private_key,
  scopes: 'https://www.googleapis.com/auth/calendar'
});

const calendar = google.calendar('v3');
process.env.DEBUG = 'dialogflow:*'; // enables lib debugging statements

const timeZone = 'America/Los_Angeles';
const timeZoneOffset = '-07:00';

exports.dialogflowFirebaseFulfillment = functions.https.onRequest((request, response) => {
  const agent = new WebhookClient({ request, response });
  console.log("Parameters", agent.parameters);
  const appointment_type = agent.parameters.AppointmentType;
  function makeAppointment (agent) {
    // Calculate appointment start and end datetimes (end = +1hr from start)
    const dateTimeStart = new Date(Date.parse(agent.parameters.date.split('T')[0] + 'T' + agent.parameters.time.split('T')[1].split('-')[0] + timeZoneOffset));
    const dateTimeEnd = new Date(new Date(dateTimeStart).setHours(dateTimeStart.getHours() + 1));
    const appointmentTimeString = dateTimeStart.toLocaleString(
      'en-US',
      { month: 'long', day: 'numeric', hour: 'numeric', timeZone: timeZone }
    );
  
    // Check the availibility of the time, and make an appointment if there is time on the calendar
    return createCalendarEvent(dateTimeStart, dateTimeEnd, appointment_type).then(() => {
      agent.add(`Ok, let me see if we can fit you in. ${appointmentTimeString} is fine!.`);
          // Insert data into a table
      addToBigQuery(agent, appointment_type);
    }).catch(() => {
      agent.add(`I'm sorry, there are no slots available for ${appointmentTimeString}.`);
    });
  }

  let intentMap = new Map();
  intentMap.set('Schedule Appointment', makeAppointment);
  agent.handleRequest(intentMap);
});


function addToBigQuery(agent, appointment_type) {
    const date_bq = agent.parameters.date.split('T')[0];
    const time_bq = agent.parameters.time.split('T')[1].split('-')[0];
    /**
    * TODO(developer): Uncomment the following lines before running the sample.
    */
    //const projectId = '<INSERT your own project ID here>'; 
    //const datasetId = "<INSERT your own dataset name here>";
    //const tableId = "<INSERT your own table name here>";
    const bigquery = new BIGQUERY({
      projectId: projectId
    });
   const rows = [{date: date_bq, time: time_bq, type: appointment_type}];
  
   bigquery
  .dataset(datasetId)
  .table(tableId)
  .insert(rows)
  .then(() => {
    console.log(`Inserted ${rows.length} rows`);
  })
  .catch(err => {
    if (err && err.name === 'PartialFailureError') {
      if (err.errors && err.errors.length > 0) {
        console.log('Insert errors:');
        err.errors.forEach(err => console.error(err));
      }
    } else {
      console.error('ERROR:', err);
    }
  });
  agent.add(`Added ${date_bq} and ${time_bq} into the table`);
}

function createCalendarEvent (dateTimeStart, dateTimeEnd, appointment_type) {
  return new Promise((resolve, reject) => {
    calendar.events.list({
      auth: serviceAccountAuth, // List events for time period
      calendarId: calendarId,
      timeMin: dateTimeStart.toISOString(),
      timeMax: dateTimeEnd.toISOString()
    }, (err, calendarResponse) => {
      // Check if there is a event already on the Calendar
      if (err || calendarResponse.data.items.length > 0) {
        reject(err || new Error('Requested time conflicts with another appointment'));
      } else {
        // Create event for the requested time period
        calendar.events.insert({ auth: serviceAccountAuth,
          calendarId: calendarId,
          resource: {summary: appointment_type +' Appointment', description: appointment_type,
            start: {dateTime: dateTimeStart},
            end: {dateTime: dateTimeEnd}}
        }, (err, event) => {
          err ? reject(err) : resolve(event);
        }
        );
      }
    });
  });
}

package.json

{
  "name": "dialogflowFirebaseFulfillment",
  "description": "Dialogflow fulfillment for the bike shop sample",
  "version": "0.0.1",
  "private": true,
  "license": "Apache Version 2.0",
  "author": "Google Inc.",
  "engines": {
    "node": "6"
  },
  "scripts": {
    "lint": "semistandard --fix \"**/*.js\"",
    "start": "firebase deploy --only functions",
    "deploy": "firebase deploy --only functions"
  },
  "dependencies": {
    "firebase-functions": "2.0.2",
    "firebase-admin": "^5.13.1",
    "actions-on-google": "2.2.0", 
    "googleapis": "^27.0.0",
    "dialogflow-fulfillment": "0.5.0",
    "@google-cloud/bigquery": "^0.12.0"
  }
}
 @priyankavergadia

Code is running but not inserting any record in BigQuery table.
Only warning message, I can see on cloud function log is - Error: Missing required header: Metadata-Flavor