Below is the working snippet in plain node.js
Functionality:
You can adapt it for your needs using the Gmail API
If you struggle with this example try Node.js Quickstart Guide
Here is the snippet:
const fs = require('fs');
const readline = require('readline');
const { google } = require('googleapis');
// If modifying these scopes, delete token.json.
const SCOPES = [
'https://mail.google.com/',
'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';
/**
* 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);
});
});
}
/********************************************************************************************
*********************************************************************************************
*********************************************************************************************
* Custom edits here
*/
let labelList = [];
function listLabels(auth) {
const gmail = google.gmail({ version: 'v1', auth });
gmail.users.labels.list({
userId: 'me',
}, (err, res) => {
if (err) return console.log('The API returned an error: ' + err);
const labels = res.data.labels;
if (labels.length) {
labels.forEach((label) => {
labelList.push(`${label.name}`);
});
} else {
console.log('No labels found.');
}
});
console.log('===listLabels finished===');
}
function makeEmailBody(to, from, subject, message) {
let str = [
"Content-Type: text/plain; charset=\"UTF-8\"\n",
"MIME-Version: 1.0\n",
"Content-Transfer-Encoding: 7bit\n",
"to: ", to, "\n",
"from: ", from, "\n",
"subject: ", subject, "\n\n",
message
].join('');
let encodedMail = new Buffer(str).toString("base64").replace(/\+/g, '-').replace(/\//g, '_');
return encodedMail;
}
function sendMessage(auth) {
let raw = makeEmailBody(
/* to */'email@gmail.com',
/* from */'email@gmail.com',
/* subject */'Subject',
/* message */`Labels:
${labelList}
`);
const gmail = google.gmail({ version: 'v1', auth });
gmail.users.messages.send({
auth: auth,
userId: 'me',
resource: {
raw: raw
}
}, (err, res) => {
return (err || res)
});
console.log('===SendMessage finished===');
}
let userId = 'email@gmail.com';
let messageId = '__id__';
function getEmail(auth){
const gmail = google.gmail({ version: 'v1', auth });
gmail.users.messages.get({
id: messageId,
userId: userId,
format: 'full'
}, (err, res) => {
if (err) return console.log('The API returned an error: ' + err);
console.log(res.data);
});
console.log('===listLabels finished===');
}
// RUN script
fs.readFile('credentials.json', (err, content) => {
if (err) {
console.log('Error loading client secret file: ' + err);
return;
}
authorize(JSON.parse(content), getEmail);
// authorize(JSON.parse(content), listLabels);
// authorize(JSON.parse(content), listFiles);
// authorize(JSON.parse(content), sendMessage);
});
How to create service account:
- Create project in Admin Console
- Create service account
- Go to Admin Console > Security > Advanced settings > Manage API client access
- In Client Name put the full email of your created Service Account
- In One or More API Scopes put https://mail.google.com/ and click Authorize
- Come back to Service accounts, select your account, Enable G Suite Domain-wide Delegation
- Create Service Account KEY (download it as .json)
- Activate Gmail API for your project. Go to APIs & Services > Dashboard, click on ENABLE APIS AND SERVICES, search for Gmail and Enable it.
Now you got service account and you can use it in your project.
