How to refresh an access token for the youtube-data-api v3

Question

I'm using v3 of the youtube data api for my server. So far I'm able to create a token by getting a code from the redirect.

                oauth2Client.getToken(req.query.code, function(err, token) {
                    if (err) {
                      console.log('Error while trying to retrieve access token', err);
                      return;
                    }
                    oauth2Client.credentials = token;
                    storeToken(token);
                    res.redirect("/channel");
                  });

I'm storing this token locally, but I have a couple questions on the following;

1. How do I check if this token is valid when a request is about to be made?
2. How do I get a new token by using the refresh token if the token I currently have is expired?

Answer 1

The best way to find out if a token is valid is to use it. In the case of an access token just use it to make a call. In the case of a refresh token the answer is the same use it to create a new access token.

The node.js client library should be handling all your refreshing of the access token for you.

The first time this code runs a file is created in TOKEN_PATH containing the consent from the user this is the refresh token. If the file exists it will be used to create a new access token as needed.

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

// If modifying these scopes, delete token.json.
const SCOPES = ['https://www.googleapis.com/auth/youtube'];
// 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('credentials.json', (err, content) => {
  if (err) return console.log('Error loading client secret file:', err);
  // Authorize a client with credentials, then call the Google Tasks API.
  authorize(JSON.parse(content), listConnectionNames);
});

/**
 * 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 getNewToken(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 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 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);
    });
  });
}