Copying data from Firebase Realtime Database to a Google Sheet in real time via Cloud Functions

firesheetz.ts

// Copyright 2017 Google LLC.
//
// 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
//
// https://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.

// Watch this code in action in this tweet:
// https://twitter.com/CodingDoug/status/940022568089554944

// 1. Follow step 1 to enable Google Sheets API in your Firebase project:
//    https://developers.google.com/sheets/api/quickstart/nodejs
//
// 2. Create a service account in your project; save the json file in the
//    functions folder; require() it to "serviceAccount".
//
// 3. Create a spreadsheet in Drive; rename the first worksheet 'Scores';
//    add Player and Score headers in row 1.
//
// 4. Share it with edit access to the email address of your service acct.
//
// 5. Copy the spreadsheet id (from its URL) to the spreadsheetId string.
//
// 6. `npm install firebase-admin firebase-functions googleapis lodash`
//
// 6. Deploy this (TypeScript) code.
//
// 7. Update the keys/values in your database under /scores and watch them
//    get updated in the sheet!

import * as functions from 'firebase-functions'
import * as google from 'googleapis'
import * as _ from 'lodash'
const sheets = google.sheets('v4')

const spreadsheetId = 'YOUR_SPREADSHEET_ID_HERE'

const serviceAccount = require('../your_service_account_credentials.json')
const jwtClient = new google.auth.JWT(
    serviceAccount.client_email,
    null,
    serviceAccount.private_key,
    ['https://www.googleapis.com/auth/spreadsheets'], // read and write sheets
    null
);

const jwtAuthPromise = new Promise((resolve, reject) => {
    jwtClient.authorize((err, tokens) => {
        console.info("Tokens", tokens)
        if (err) {
          console.error(err)
          reject(err)
          return
        }
        resolve(tokens)
    })
})

export const copyScoresToSheet = functions.database.ref('/scores').onUpdate(event => {
    const data = event.data.val()
    console.info(data)

    // Sort the scores.  scores is an array of arrays each containing name and score.
    const scores = _.map<any, [string, number]>(data, (value, key) => [String(key), value])
    scores.sort((a,b) => {return b[1] - a[1]})

    return jwtAuthPromise.then(tokens => {
        return new Promise((resolve, reject) => {
            sheets.spreadsheets.values.update({
                auth: jwtClient,
                spreadsheetId: spreadsheetId,
                range: 'Scores!A2:B7',  // update this range of cells
                valueInputOption: 'RAW',
                resource: { values: scores }
            }, (err, result) => {
                if (err) {
                    console.log(err)
                    reject(err)
                    return
                }
                console.log(result)
                resolve(result)
            })
        })
    })
})