How to Use GMAIL API with NodeJs Part-1
This will be a 3 part series. In the first one, we will connect our application with the user’s gmail account. In the second, we will create and send emails, save , delete and list all drafts in the user’s account. And in the third, we list all mails in user’s inbox and parse the mail body.
By the end of third article, you will have an automatic script to open all medium daily digest articles in your default browser.
Pre-requisites
To begin with, head over to Official Guide and click on the Enable Gmail-Api button and it should download the credentials.json file. Save it in your project directory.
Run the following command in your terminal to install googleapis library
npm install googleapis --saveNow create an index.js file and paste the code below. Don’t worry, it’s a well-commented code. 😏
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/gmail.readonly','https://www.googleapis.com/auth/gmail.modify',
'https://www.googleapis.com/auth/gmail.compose','https://www.googleapis.com/auth/gmail.send'];
// 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 the client with credentials, then call the Gmail API.
authorize(JSON.parse(content), getAuth);
});
/**
* 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);
});
});
}
function getAuth(auth){
}
When you run the code for the first time, you will have to follow the link that shows up in the terminal. Allow the application the permissions it needs. You will now get a key, paste it into the terminal and hit enter.
You have now successfully connected you application with your gmail Id. Cheers. 🍻
Note that if you modify the SCOPES array, don’t forget to delete the token.json file. So next time when you run the code, it will automatically generate a new token.json file.
The authorize and getNewToken functions are responsible for the authorization process and the token key generated.
The getAuth function is where we put our custom code.
Note that it is passed as a callback and will execute only on the completion of the authorization process. Also, the auth parameter passed in the function will be used in all the requests we make.
One down, two to go!
See you in the next article!