Read a Google Sheet in Node.js with NPM 🤓

— 9 minute read

When it comes to databases, we often think about a SQL database or NoSQL alternative, but have you consider Google Sheets?

Huh, wait what? YES, Google Sheets can serve as a data store!

So in this tutorial, we will make a Node.js script that can read data from a Google Sheet via their API.

It will look like this:

Node Google spreadsheet access

Starting the project

We will be starting the project from scratch, first, let's set up a new node project:

npm init

You can follow the prompts here. Nothing special needed

More info about starting a Node JS app here.

Next step, let's install the Google API package to access Google Sheets data:

npm install googleapis@39 --save

That's really it!

Now we need to download our credentials.json file from Google.

Visit the following URL and click the Enable the Google Sheets API button.

Google Quickstart

Copy the credentials.json file into your project.

Create Node.js script with the Google API

There we go, we will be using the Google provided Node.js script to get started with.

Create an index.js file in your project.

We start by defining our variables

const fs = require('fs');
const readline = require('readline');
const {google} = require('googleapis');

Then we need to tell Google which API's we want to use:

const SCOPES = ['https://www.googleapis.com/auth/spreadsheets.readonly'];

And define an empty token.json path (Google will store our token there)

const TOKEN_PATH = 'token.json';

Then we need to read out the credentials file and authorize with Google!

And when that is all done, we will call our listMajors function which is the main function!

fs.readFile('credentials.json', (err, content) => {
  if (err) return console.log('Error loading client secret file:', err);
  authorize(JSON.parse(content), listMajors);
});

Ok, let's make that authorize function!

function authorize(credentials, callback) {
  const {client_secret, client_id, redirect_uris} = credentials.installed;
  const oAuth2Client = new google.auth.OAuth2(client_id, client_secret, redirect_uris[0]);

  fs.readFile(TOKEN_PATH, (err, token) => {
    if (err) return getNewToken(oAuth2Client, callback);
    oAuth2Client.setCredentials(JSON.parse(token));
    callback(oAuth2Client);
  });
}

We are defining our credentials as received from the file and create a new OAuth client. Then we start a new token.json file and call the getNewToken function.

function getNewToken(oAuth2Client, callback) {
  const authUrl = oAuth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: SCOPES,
  });
  console.log('Authorize this app by visiting this url:', authUrl);
  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  });
  rl.question('Enter the code from that page here: ', (code) => {
    rl.close();
    oAuth2Client.getToken(code, (err, token) => {
      if (err) return console.error('Error while trying to retrieve access token', err);
      oAuth2Client.setCredentials(token);
      fs.writeFile(TOKEN_PATH, JSON.stringify(token), (err) => {
        if (err) return console.error(err);
        console.log('Token stored to', TOKEN_PATH);
      });
      callback(oAuth2Client);
    });
  });
}

This is a bit of a wow, what's happening. But when we run our function, we get prompted to visit a URL. We must then visit it and give Google access to our spreadsheets. We will get a code back, which we paste. After then our token will be created!

Run Node script with Google Sheets API

Confirm Access to Google Account

Read data from Google Sheets in Node JS

To make the actual function that reads from the Google spreadsheet (listMajors) we use the following code:

function listMajors(auth) {
  const sheets = google.sheets({version: 'v4', auth});
  sheets.spreadsheets.values.get(
    {
      spreadsheetId: '1BxiMVs0XRA5nFMdKvBdBZjgmUUqptlbs74OgvE2upms',
      range: 'Class Data!A2:E',
    },
    (err, res) => {
      if (err) return console.log('The API returned an error: ' + err);
      const rows = res.data.values;
      if (rows.length) {
        console.log('Name, Major:');
        // Print columns A and E, which correspond to indices 0 and 4.
        rows.map((row) => {
          console.log(`${row[0]}, ${row[4]}`);
        });
      } else {
        console.log('No data found.');
      }
    }
  );
}

So, we start by defining a new Google Sheets API, passing it our Authentication credentials. Then we call values.get where we pass a spreadsheet ID, and a range of cells.

Note: This ID is the default Google Testing document!

Then once we get the data, we console.log the specific data back to the console!

There you go, we now made a Node JS script that can read from a Google Sheet.

Running our Node JS script

We can run the script by executing the following command:

node .

When putting this code in Git, make sure to keep your credentials and token safe 🤓

You can find my full code on GitHub or on Google.

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