Google Analytics with node.js

Not all of the Google APIs contain sample code for every language. I noticed recently that there wasnt a node.js sample for the Google Analytics reporting api. I thought we would take a quick look at it.

Setup

Your Package.json should look as follows. I have included the googlepais library as well as dotenv for storage of env vars.

{
  "name": "google_nodejs_samples",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "description": "A simple Node.js command-line application that makes requests to the Google API.",
  "private": true,
  "dependencies": {
    "dotenv": "^8.2.0",
    "googleapis": "^39.0.0"
  },
  "devDependencies": {},
  "engines": {
    "node": ">=6.4.0"
  },
  "scripts": {
    "start": "node ."
  }
}

For the .env file i have stored two env vars here the fist being the json cred file and the second being the view id we will be requesting data for.

# API
API_CREDS=/home/linda/development/creds/client.json
VIEW_ID=78110423

The code

Now we have the code used to request data from Google Analytics. This code is based off of one of the official node.js samples. it simply requests users for a week.

const fs = require('fs');
const readline = require('readline');
const {google} = require('googleapis');
const dotenv = require('dotenv');
dotenv.config();
const CRED_FILE_PATH = process.env.API_CREDS;
console.log(`Your cred path is ${CRED_FILE_PATH}`); // ../creds.json
const VIEW_ID = process.env.VIEW_ID;
console.log(`Your view id is ${VIEW_ID}`);

// If modifying these scopes, delete token.json.
const SCOPES = ['https://www.googleapis.com/auth/analytics.readonly'];
// The file token.json stores the user's access and refresh tokens, and is
// created automatically when the authorization flow completes for the first
// time.
const TOKEN_PATH = 'token.json';

// Load client secrets from a local file.
fs.readFile(CRED_FILE_PATH, (err, content) => {
    if (err) return console.log('Error loading client secret file:', err);
    // Authorize a client with credentials, then call the Google Drive API.
    authorize(JSON.parse(content), getUserReport);
});

/**
 * Create an OAuth2 client with the given credentials, and then execute the
 * given callback function.
 * @param {Object} credentials The authorization client credentials.
 * @param {function} callback The callback to call with the authorized client.
 */
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]);

    // Check if we have previously stored a token.
    fs.readFile(TOKEN_PATH, (err, token) => {
        if (err) return getAccessToken(oAuth2Client, callback);
        oAuth2Client.setCredentials(JSON.parse(token));
        callback(oAuth2Client);
    });
}

/**
 * Get and store new token after prompting for user authorization, and then
 * execute the given callback with the authorized OAuth2 client.
 * @param {google.auth.OAuth2} oAuth2Client The OAuth2 client to get token for.
 * @param {getEventsCallback} callback The callback for the authorized client.
 */
function getAccessToken(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 retrieving access token', err);
            oAuth2Client.setCredentials(token);
            // Store the token to disk for later program executions
            fs.writeFile(TOKEN_PATH, JSON.stringify(token), (err) => {
                if (err) return console.error(err);
                console.log('Token stored to', TOKEN_PATH);
            });
            callback(oAuth2Client);
        });
    });
}

/**
 * Number of users between last week and two weeks ago.
 * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
 */
function getUserReport(auth) {
    const service = google.analyticsreporting({version: 'v4', auth});
    const googleAnalyticsReports = {
        resource: {
            reportRequests: [{
                viewId: VIEW_ID,
                dateRanges: [
                    {
                        startDate: '14daysAgo',
                        endDate: '7daysAgo'
                    }
                ],
                metrics: [
                    {
                        expression: 'ga:users'
                    }
                ]
            }]
        }
    };

    service.reports.batchGet(googleAnalyticsReports, (err, res) => {
        if (err) return console.log('The API returned an error: ' + err);
        const reports = res.data.reports;
        if (reports.length) {
            console.log('Reports:');
            reports.forEach(report => {
                console.log('\tMetrics:');
                report.columnHeader.metricHeader.metricHeaderEntries.forEach(metricHeader => console.log('\t\t', metricHeader.name))
                report.data.rows.forEach(row => console.log('\t\t', row.metrics))
                }
            );

        } else {
            console.log('No data found.');
        }
    });
}

Conclusion

The above sample is a very simple example of connecting to Google Analytics using Oauth2 and requesting data. It uses the Google APIs node Js client library in order to make its requests.